Genomes and Genes
Gene Symbol: B4galnt1
Description: beta-1,4-N-acetyl-galactosaminyl transferase 1
Alias: 4933429D13Rik, Gal-NAc-T, GalNAc-T, GalNAcT, Galgt1, Ggm-2, Ggm2, beta-1,4 N-acetylgalactosaminyltransferase 1, (N-acetylneuraminyl)-galactosylglucosylceramide, GM2/GD2 synthase, UDP-N-acetyl-alpha-D-galactosamine:(N-acetylneuraminyl)-galactosylglucosylceramide-beta-1, 4-N-acetylgalactosaminyltransferase, beta1,4GalNAC-T
- Lunn M, Johnson L, Fromholt S, Itonori S, Huang J, Vyas A, et al. High-affinity anti-ganglioside IgG antibodies raised in complex ganglioside knockout mice: reexamination of GD1a immunolocalization. J Neurochem. 2000;75:404-12 pubmed
- Liu Y, Wada R, Kawai H, Sango K, Deng C, Tai T, et al. A genetic model of substrate deprivation therapy for a glycosphingolipid storage disorder. J Clin Invest. 1999;103:497-505 pubmed..The results support the validity of the substrate deprivation therapy and also highlight some limitations...
- Takamiya K, Yamamoto A, Yamashiro S, Shin M, Okada M, Fukumoto S, et al. Mice with disrupted GM2/GD2 synthase gene lack complex gangliosides but exhibit only subtle defects in their nervous system. Proc Natl Acad Sci U S A. 1996;93:10662-7 pubmed..The higher levels of GM3 and GD3 expressed in the brains of these mutant mice may be able to compensate for the lack of complex gangliosides. ..
- Ohmi Y, Tajima O, Ohkawa Y, Yamauchi Y, Sugiura Y, Furukawa K, et al. Gangliosides are essential in the protection of inflammation and neurodegeneration via maintenance of lipid rafts: elucidation by a series of ganglioside-deficient mutant mice. J Neurochem. 2011;116:926-35 pubmed publisher..These results indicate that destruction of GEM/rafts is caused by ganglioside deficiency with gradual intensity depending on the degree of defects of their compositions. ..
- Kawai H, Allende M, Wada R, Kono M, Sango K, Deng C, et al. Mice expressing only monosialoganglioside GM3 exhibit lethal audiogenic seizures. J Biol Chem. 2001;276:6885-8 pubmed..restrict the expression of gangliosides, the GD3S mutant mice were crossbred with mice carrying a disrupted GalNAcT gene encoding beta1,4-N-acetylgalactosaminyltransferase...
- Rummel A, Eichner T, Weil T, Karnath T, Gutcaits A, Mahrhold S, et al. Identification of the protein receptor binding site of botulinum neurotoxins B and G proves the double-receptor concept. Proc Natl Acad Sci U S A. 2007;104:359-64 pubmed..The molecular characterization of the synaptotagmin binding site provides the basis for designing a novel class of potent binding inhibitors. ..
- Fukumoto S, Yamamoto A, Hasegawa T, Abe K, Takamiya K, Okada M, et al. Genetic remodeling of gangliosides resulted in the enhanced reactions to the foreign substances in skin. Glycobiology. 1997;7:1111-20 pubmed..Main cell population in these inflammatory reactions consisted of neutrophils, suggesting an increased sensitivity of neutrophils to chemotactic factors in the transgenic mice. ..
- Furukawa K, Aixinjueluo W, Kasama T, Ohkawa Y, Yoshihara M, Ohmi Y, et al. Disruption of GM2/GD2 synthase gene resulted in overt expression of 9-O-acetyl GD3 irrespective of Tis21. J Neurochem. 2008;105:1057-66 pubmed publisher..Increased 9-O-acetyl GD3, in addition to GM3 and GD3, may play an important role in the compensation for deleted complex gangliosides in the mutant mice. ..
- Dobrović B, Curić G, Petanjek Z, Heffer M. Dendritic morphology and spine density is not altered in motor cortex and dentate granular cells in mice lacking the ganglioside biosynthetic gene B4galnt1 - A quantitative Golgi cox study. Coll Antropol. 2011;35 Suppl 1:25-30 pubmed..To define maturation of cortical neurons in mice lacking B4galnt1 we performed a morphological analysis of Golgi-Cox impregnated pyramidal neurons in primary motor cortex and ..
- Wu G, Lu Z, Wang J, Wang Y, Xie X, Meyenhofer M, et al. Enhanced susceptibility to kainate-induced seizures, neuronal apoptosis, and death in mice lacking gangliotetraose gangliosides: protection with LIGA 20, a membrane-permeant analog of GM1. J Neurosci. 2005;25:11014-22 pubmed..KO) mice lacking gangliotetraose gangliosides attributable to disruption of the gene for GM2/GD2 synthase [GalNAcT (UDP-N-acetylgalactosamine:GM3/GD3 beta-1,4-N-acetylgalactosaminyltransferase; EC 2.4.1...
- Yamashita T, Wu Y, Sandhoff R, Werth N, Mizukami H, Ellis J, et al. Interruption of ganglioside synthesis produces central nervous system degeneration and altered axon-glial interactions. Proc Natl Acad Sci U S A. 2005;102:2725-30 pubmed..null mutations in two critical ganglioside-specific glycosyltransferase genes, Siat9 (encoding GM3 synthase) and Galgt1 (encoding GM2 synthase), were generated...
- Tenno M, Ohtsubo K, Hagen F, Ditto D, Zarbock A, Schaerli P, et al. Initiation of protein O glycosylation by the polypeptide GalNAcT-1 in vascular biology and humoral immunity. Mol Cell Biol. 2007;27:8783-96 pubmed..These findings reveal that the initiation of protein O glycosylation by ppGalNAcT-1 provides a distinctive repertoire of advantageous functions that support vascular responses and humoral immunity. ..
- Sandhoff R, Geyer R, Jennemann R, Paret C, Kiss E, Yamashita T, et al. Novel class of glycosphingolipids involved in male fertility. J Biol Chem. 2005;280:27310-8 pubmed..Mutant mice strains deficient in specific genes encoding biosynthetic enzymes of the GSL pathway including Galgt1 (encoding GM2 synthase) and Siat9 (encoding GM3 synthase) have been established lacking various overlapping ..
- Pan B, Fromholt S, Hess E, Crawford T, Griffin J, Sheikh K, et al. Myelin-associated glycoprotein and complementary axonal ligands, gangliosides, mediate axon stability in the CNS and PNS: neuropathology and behavioral deficits in single- and double-null mice. Exp Neurol. 2005;195:208-17 pubmed..Mice lacking the ganglioside biosynthetic gene Galgt1 fail to express complex gangliosides, including GD1a and GT1b...
- Zitman F, Todorov B, Jacobs B, Verschuuren J, Furukawa K, Willison H, et al. Neuromuscular synaptic function in mice lacking major subsets of gangliosides. Neuroscience. 2008;156:885-97 pubmed publisher..Rather, presynaptic gangliosides appear to play a modulating role in temperature- and use-dependent fine-tuning of transmitter output. ..
- Dong M, Tepp W, Liu H, Johnson E, Chapman E. Mechanism of botulinum neurotoxin B and G entry into hippocampal neurons. J Cell Biol. 2007;179:1511-22 pubmed..These data suggest that gangliosides are the shared coreceptor for BoNT/A, B, and G, supporting a double-receptor model for these three BoNTs for which the protein receptors are known. ..
- Hennet T, Hagen F, Tabak L, Marth J. T-cell-specific deletion of a polypeptide N-acetylgalactosaminyl-transferase gene by site-directed recombination. Proc Natl Acad Sci U S A. 1995;92:12070-4 pubmed..These results indicate a complexity in vertebrate O-glycan biosynthesis that involves multiple polypeptide GalNAc-Ts. We infer the potential for protein-specific O-glycan formation governed by distinct polypeptide GalNAc-Ts. ..
- Sun J, Shaper N, Itonori S, Heffer Lauc M, Sheikh K, Schnaar R. Myelin-associated glycoprotein (Siglec-4) expression is progressively and selectively decreased in the brains of mice lacking complex gangliosides. Glycobiology. 2004;14:851-7 pubmed..Mice with a disrupted Galgt1 gene lack UDP-GalNAc:GM3/GD3 N-acetylgalactosaminyltransferase (GM2/GD2 synthase) and fail to express complex ..
- Chiavegatto S, Sun J, Nelson R, Schnaar R. A functional role for complex gangliosides: motor deficits in GM2/GD2 synthase knockout mice. Exp Neurol. 2000;166:227-34 pubmed..1999. Mice lacking complex gangliosides develop Wallerian degeneration and myelination defects. Proc. Natl. Acad. Sci. USA 96: 7532-7537), and may provide insights into the mechanisms underlying certain neural degenerative diseases. ..
- Hashimoto Y, Abe M, Kiuchi Y, Suzuki A, Yamakawa T. Genetically regulated expression of UDP-N-acetylgalactosamine: GM3(NeuGc) N-acetylgalactosaminyltransferase [EC 188.8.131.52] activity in mouse liver. J Biochem. 1984;95:1543-9 pubmed..These results suggest that the expression of GM2(NeuGc) is directly regulated by the activity of UDP-N-acetylgalactosamine: GM3(NeuGc) N-acetylgalactosaminyltransferase in mouse liver. ..
- Olvera Gomez I, Hamilton S, Xiao Z, Guimaraes C, Ploegh H, Hogquist K, et al. Cholera toxin activates nonconventional adjuvant pathways that induce protective CD8 T-cell responses after epicutaneous vaccination. Proc Natl Acad Sci U S A. 2012;109:2072-7 pubmed publisher..Chemoenzymatic generation of CT-antigen fusion proteins led to efficient priming of the CD8 T-cell responses, paving the way for development of this immunization strategy as a therapeutic option. ..
- Saito M, Wu G, Hui M, Masiello K, Dobrenis K, Ledeen R, et al. Ganglioside accumulation in activated glia in the developing brain: comparison between WT and GalNAcT KO mice. J Lipid Res. 2015;56:1434-48 pubmed publisher..Thus, GM2 elevation is associated with activation of microglia and astrocytes in the injured developing brain, and GM2, GD2, or other downstream gangliosides may regulate astroglial responses in ethanol-induced neurodegeneration. ..
- You J, O Hara S, Velupillai P, Castle S, LEVERY S, Garcea R, et al. Ganglioside and Non-ganglioside Mediated Host Responses to the Mouse Polyomavirus. PLoS Pathog. 2015;11:e1005175 pubmed publisher..Thus, while gangliosides are essential for infection in the animal, gangliosides are not required for mitogenic responses and innate immune responses to the virus. ..
- Greenshields K, Halstead S, Zitman F, Rinaldi S, Brennan K, O Leary C, et al. The neuropathic potential of anti-GM1 autoantibodies is regulated by the local glycolipid environment in mice. J Clin Invest. 2009;119:595-610 pubmed publisher..This revised understanding of the complexities in ganglioside membrane topology provides a mechanistic account for wide variations in the neuropathic potential of anti-GM1 antibodies. ..
- Wu G, Xie X, Lu Z, Ledeen R. Cerebellar neurons lacking complex gangliosides degenerate in the presence of depolarizing levels of potassium. Proc Natl Acad Sci U S A. 2001;98:307-12 pubmed
- Buch M, Liaci A, O Hara S, Garcea R, Neu U, Stehle T. Structural and Functional Analysis of Murine Polyomavirus Capsid Proteins Establish the Determinants of Ligand Recognition and Pathogenicity. PLoS Pathog. 2015;11:e1005104 pubmed publisher..Moreover, the amino acid exchanges have subtle effects on their affinity for the validated receptor GD1a. Our results indicate that both receptor specificity and affinity influence MuPyV pathogenesis. ..
- Zhang G, Bogdanova N, Gao T, Song J, Cragg M, Glennie M, et al. Fc? receptor-mediated inflammation inhibits axon regeneration. PLoS ONE. 2014;9:e88703 pubmed publisher..Our results add to the complexity of axon regeneration in injured peripheral and central nervous systems as adverse effects of B cells and autoantibodies on neural injury and repair are increasingly recognized. ..
- Strotmeier J, Mahrhold S, Krez N, Janzen C, Lou J, Marks J, et al. Identification of the synaptic vesicle glycoprotein 2 receptor binding site in botulinum neurotoxin A. FEBS Lett. 2014;588:1087-93 pubmed publisher..The dimension of the binding pocket was characterised in detail by site directed mutagenesis allowing the development of potent inhibitors as well as modifying receptor binding properties. ..
- Suzuki A, Hashimoto Y, Abe M, Kiuchi Y, Yamakawa T. Genetic regulation of GM2 (NeuGc) expression in liver of mouse. Adv Exp Med Biol. 1984;174:263-72 pubmed..It is a subject for further study to elucidate what kind of defect is involved in the GM2 (NeuGc) biosynthesis of WHT/Ht liver. ..
- Takamiya K, Yamamoto A, Yamashiro S, Haraguchi M, Okada M, Ikeda T, et al. T cell receptor-mediated stimulation of mouse thymocytes induces up-regulation of the GM2/GD2 synthase gene. FEBS Lett. 1995;358:79-83 pubmed..In situ hybridization showed an elevation of mRNA levels in medullar thymocytes, suggesting that T cell receptor-mediated signaling induces up-regulation of the GM2/GD2 synthase gene in mature thymocytes. ..
- Ma Q, Kobayashi M, Sugiura M, Ozaki N, Nishio K, Shiraishi Y, et al. Morphological study of disordered myelination and the degeneration of nerve fibers in the spinal cord of mice lacking complex gangliosides. Arch Histol Cytol. 2003;66:37-44 pubmed
- Bullens R, O Hanlon G, Wagner E, Molenaar P, Furukawa K, Furukawa K, et al. Complex gangliosides at the neuromuscular junction are membrane receptors for autoantibodies and botulinum neurotoxin but redundant for normal synaptic function. J Neurosci. 2002;22:6876-84 pubmed..These data prove the critical importance of complex gangliosides in mediating pathophysiological events at the neuromuscular synapse. ..
- Zhao J, Fukumoto S, Okada M, Furugen R, Miyazaki H, Takamiya K, et al. Attenuation of interleukin 2 signal in the spleen cells of complex ganglioside-lacking mice. J Biol Chem. 1999;274:13744-7 pubmed
- Mohammed E, Snella E, Rutz Mendicino M, Echevarria F, Awedikian R, Whitley E, et al. Accelerated clinical disease and pathology in mucopolysaccharidosis type IIIB and GalNAc transferase double knockout mice. Mol Genet Metab. 2012;107:129-35 pubmed publisher..Contrary to our expectation and to double knockout (DKO) studies where GalNAcT was knocked out in combination with other LSDs, our DKO mice showed a drastically shortened lifespan (24.5±1...
- Sango K, Johnson O, Kozak C, Proia R. beta-1,4-N-Acetylgalactosaminyltransferase involved in ganglioside synthesis: cDNA sequence, expression, and chromosome mapping of the mouse gene. Genomics. 1995;27:362-5 pubmed..mRNA expression in adult tissues and in embryos, and determined the chromosomal location of the GalNAc-T gene, Ggm2. In comparison with the human cDNA, the mouse sequence was 83 and 87% identical at the nucleic acid and amino acid ..
- Ohmi Y, Ohkawa Y, Tajima O, Sugiura Y, Furukawa K, Furukawa K. Ganglioside deficiency causes inflammation and neurodegeneration via the activation of complement system in the spinal cord. J Neuroinflammation. 2014;11:61 pubmed publisher..Gene profiling revealed that inflammation and neurodegeneration in the spinal cord of DKO mice are, at least partly, dependent on complement activation. ..
- Tessitore A, Del P Martin M, Sano R, Ma Y, Mann L, Ingrassia A, et al. GM1-ganglioside-mediated activation of the unfolded protein response causes neuronal death in a neurodegenerative gangliosidosis. Mol Cell. 2004;15:753-66 pubmed..of UPR pathways did not occur in mice double deficient for beta-gal and ganglioside synthase, beta-gal-/-/GalNAcT-/-, which do not accumulate GM1...
- GONDRE LEWIS M, McGlynn R, Walkley S. Cholesterol accumulation in NPC1-deficient neurons is ganglioside dependent. Curr Biol. 2003;13:1324-9 pubmed..gangliosides by creating mice doubly deficient in both NPC1 and the GSL synthetic enzyme, GM2/GD2 synthase (GalNAcT)...
- Takamiya K, Yamamoto A, Zhao J, Fukumoto S, Yamashiro S, Okada M, et al. Complex gangliosides are essential in spermatogenesis of mice: possible roles in the transport of testosterone. Proc Natl Acad Sci U S A. 1998;95:12147-52 pubmed..These results suggested that complex gangliosides are essential in the transport of testosterone to the seminiferous tubules and bloodstream from Leydig cells. Our results provide insights into roles of gangliosides in vivo. ..
- Sandhoff R, Hepbildikler S, Jennemann R, Geyer R, Gieselmann V, Proia R, et al. Kidney sulfatides in mouse models of inherited glycosphingolipid disorders: determination by nano-electrospray ionization tandem mass spectrometry. J Biol Chem. 2002;277:20386-98 pubmed..and beta-subunits (Hexa-/- and Hexb-/-), GD3 synthase (GD3S-/-), GD3 synthase and GalNAc transferase (GD3S-/- and GalNAcT-/-), GM2 activator protein (Gm2a-/-), or arylsulfatase A (ASA-/-)...
- Yao D, McGonigal R, Barrie J, Cappell J, Cunningham M, Meehan G, et al. Neuronal expression of GalNAc transferase is sufficient to prevent the age-related neurodegenerative phenotype of complex ganglioside-deficient mice. J Neurosci. 2014;34:880-91 pubmed publisher..Mice lacking complex gangliosides attributable to targeted ablation of the B4galnt1 gene that encodes ?-1,4-N-acetylegalactosaminyltransferase 1 (GalNAc-transferase; GalNAcT(-/-)) develop normally ..
- Matsumoto Y, Yuki N, Van Kaer L, Furukawa K, Hirata K, Sugita M. Cutting edge: Guillain-Barre syndrome-associated IgG responses to gangliosides are generated independently of CD1 function in mice. J Immunol. 2008;180:39-43 pubmed..Thus, these results indicate CD1-independent pathways for anti-ganglioside Ab production. ..
- Porubsky S, Speak A, Salio M, Jennemann R, Bonrouhi M, Zafarulla R, et al. Globosides but not isoglobosides can impact the development of invariant NKT cells and their interaction with dendritic cells. J Immunol. 2012;189:3007-17 pubmed publisher..Moreover, in ?GalA(-/-) mice, it is the Gb3 storage that is responsible for the decreased iNKT cell numbers and impeded Ag presentation on DCs. ..
- Yamamoto A, Haraguchi M, Yamashiro S, Fukumoto S, Takamiya K, Atsuta M, et al. Heterogeneity in the expression pattern of two ganglioside synthase genes during mouse brain development. J Neurochem. 1996;66:26-34 pubmed
- Singhal N, Xu R, Martin P. Distinct contributions of Galgt1 and Galgt2 to carbohydrate expression and function at the mouse neuromuscular junction. Mol Cell Neurosci. 2012;51:112-26 pubmed publisher..Here we show that Galgt1, which synthesizes the ?1,4GalNAc linkage of the CT carbohydrate on gangliosides, is required for presynaptic ..
- Bhuiyan R, Kondo Y, Yamaguchi T, Tokuda N, Ohkawa Y, Hashimoto N, et al. Expression analysis of 0-series gangliosides in human cancer cell lines with monoclonal antibodies generated using knockout mice of ganglioside synthase genes. Glycobiology. 2016;26:984-998 pubmed..We used GM2/GD2 synthase (B4galnt1)-deficient mice to immunize by liposomes embedded with GD1Î± or acidic glycolipid fractions from brain of ..
- Oda M, Kabura M, Takagishi T, Suzue A, Tominaga K, Urano S, et al. Clostridium perfringens alpha-toxin recognizes the GM1a-TrkA complex. J Biol Chem. 2012;287:33070-9 pubmed..Therefore, we conclude that GM1a is the primary cellular receptor for alpha-toxin, which can be a potential target for drug developed against this pathogen. ..
- Caterina J, Shi J, Kozak C, Engler J, Birkedal Hansen H. Characterization, expression analysis and chromosomal mapping of mouse matrix metalloproteinase-19 (MMP-19). Mol Biol Rep. 2000;27:73-9 pubmed..The COOH-terminal serine and threonine-rich domain is considerably longer in the mouse homologue. The mouse MMP-19 gene maps to very distal end of mouse chromosome 10. ..
- Kondo Y, Tokuda N, Fan X, Yamashita T, Honke K, Takematsu H, et al. Glycosphingolipids are not pivotal receptors for Subtilase cytotoxin in vivo: sensitivity analysis with glycosylation-defective mutant mice. Biochem Biophys Res Commun. 2009;378:179-81 pubmed publisher..5 microg) of SubAB as well as wild type mice. These results indicated none of glycolipids are not pivotal receptor for SubAB in the body. ..
- Van Dyken S, Green R, Marth J. Structural and mechanistic features of protein O glycosylation linked to CD8+ T-cell apoptosis. Mol Cell Biol. 2007;27:1096-111 pubmed..We propose that an endogenous lectin activates an apoptotic pathway constructed in CD8+ T cells following TCR stimulation and enables contraction upon attenuation of immune signaling. ..
- Rabionet M, Bayerle A, Jennemann R, Heid H, Fuchser J, Marsching C, et al. Male meiotic cytokinesis requires ceramide synthase 3-dependent sphingolipids with unique membrane anchors. Hum Mol Genet. 2015;24:4792-808 pubmed publisher..Hence, testis-specific SLs, which we also link to CerS3 in human testis, are quintessential for male fertility. ..
- Zhou S, Davidson C, McGlynn R, Stephney G, Dobrenis K, Vanier M, et al. Endosomal/lysosomal processing of gangliosides affects neuronal cholesterol sequestration in Niemann-Pick disease type C. Am J Pathol. 2011;179:890-902 pubmed publisher..These studies provide further evidence that NPC1 and NPC2 proteins participate in endosomal/lysosomal processing of both sphingolipids and cholesterol. ..
- Prendergast J, Umanah G, Yoo S, LagerlÃ¶f O, Motari M, Cole R, et al. Ganglioside regulation of AMPA receptor trafficking. J Neurosci. 2014;34:13246-58 pubmed publisher..Disrupting ganglioside biosynthesis may result in reduced synaptic expression of GluR2-contianing AMPARs resulting in intellectual deficits and seizure susceptibility in mice and humans. ..
- Hashimoto Y, Otsuka H, Sudo K, Suzuki K, Suzuki A, Yamakawa T. Genetic regulation of GM2 expression in liver of mouse. J Biochem. 1983;93:895-901 pubmed
- Liu Y, Wu Y, Wada R, Neufeld E, Mullin K, Howard A, et al. Alleviation of neuronal ganglioside storage does not improve the clinical course of the Niemann-Pick C disease mouse. Hum Mol Genet. 2000;9:1087-92 pubmed..is a crucial factor in neuropathogenesis, we bred NP-C model mice with mice carrying a targeted mutation in GalNAcT, the gene encoding the beta-1-4GalNAc transferase responsible for the synthesis of GM2 and complex gangliosides...
- Tsai Y, Yu R. Epigenetic activation of mouse ganglioside synthase genes: implications for neurogenesis. J Neurochem. 2014;128:101-10 pubmed publisher..As a consequence, the level of each GT mRNA was increased correspondingly. Hyperacetylation of histones on the GalNAcT promoter resulted in recruitment of the trans-activation factors Sp2 and AP-1 when cellular histone deacetylases ..
- Wang J, Lu Z, Gabius H, Rohowsky Kochan C, Ledeen R, Wu G. Cross-linking of GM1 ganglioside by galectin-1 mediates regulatory T cell activity involving TRPC5 channel activation: possible role in suppressing experimental autoimmune encephalomyelitis. J Immunol. 2009;182:4036-45 pubmed publisher..Our results thus indicate GM1 in Teff cells to be the primary target of Gal-1 expressed by Treg cells, the resulting co-cross-linking and TRPC5 channel activation contributing importantly to the mechanism of autoimmune suppression. ..
- Rabionet M, van der Spoel A, Chuang C, von Tümpling Radosta B, Litjens M, Bouwmeester D, et al. Male germ cells require polyenoic sphingolipids with complex glycosylation for completion of meiosis: a link to ceramide synthase-3. J Biol Chem. 2008;283:13357-69 pubmed publisher..Nevertheless, sterile Galgt1(-/-) mice, with a defective meiotic cytokinesis and a subsequent block in spermiogenesis, lacked complex but ..
- Sokoloff D, Hechtman P. Genetic control of ganglioside biosynthesis in mice. Biochem Genet. 1988;26:631-44 pubmed..3-9.0. The simplest mode of action of genes which control the enzymatic phenotype that would be consistent with these findings are one or two structural genes or one or two cis-regulatory genes affecting the rate of enzyme synthesis. ..