SAC6

..Two round bud mutants (arc18 and sac6) were found to be defective in apical actin patch localization...

..Thus, MID2 and ZEO1 appear to play reciprocal roles in the modulation of the yeast PKC1-MPK1 cell integrity pathway...

..Its protein product, Sac6p (previously referred to as ABP67), was independently isolated by actin-filament affinity chromatography and colocalizes with actin in vivo...

..ABP1, mutations that create a requirement for this protein have now been isolated in the previously identified gene SAC6 and in two new genes, SLA1 and SLA2. The SAC6 gene encodes yeast fimbrin, an actin filament-bundling protein...

..Studies in yeast and mammalian cells indicate that Abp1p is involved functionally in endocytosis. Based on these results, we speculate that Abp1p may link Arp2/3-mediated actin assembly to a specific step in endocytosis...

..is a novel component of yeast cortical actin patches and shares in vivo functions and biochemical activities with Sac6/fimbrin, the one other actin patch component that contains CH domains...

..Our data support a role for Scp1p in bundling actin filaments and, in concert with Sac6p, acting as a second actin-bundling activity crucial to the stability of the yeast actin cytoskeleton...

..Mutations in this actin subdomain were shown to be, like a null allele of the yeast fimbrin gene (SAC6), lethal in combination with null mutations in the ABP1 and SLA2 genes, and viable in combination with a null ..

..on actin that interacts with Sac6p, we have analyzed eight different act1 mutations that show suppression with sac6 mutant alleles, and have asked whether (a) these mutations occur in a small defined region on the crystal structure ..

..was reduced, some genetic backgrounds (prk1 Delta and sla1 Delta) tolerated large affinity reductions while others (sac6 Delta and sla2 Delta) were much more sensitive to these reductions...

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The protein encoded by SAC6, a gene that can mutate to suppress a temperature-sensitive defect in the yeast actin gene, has been identified as a 67-kilodalton actin-binding protein (ABP 67) that associates with all identifiable actin ..

..Furthermore, results of double-mutant analyses suggest that Ark1p and Prk1p function in overlapping but distinct pathways that regulate the cortical actin cytoskeleton...

..Monogenic inheritance was found for four mutations, which were attributed to three genetic loci. One mutation, sac6-69, is in the gene encoding fimbrin, another actin-binding protein, which was expected because null mutations in ..

..1995. Cell. 81:591-600). In addition, we find that the unpolymerized pool of actin in yeast is very small relative to that found in higher cells, which suggests that actin filament assembly is less dynamic in yeast than higher cells...

..Conversely, increased turgor pressure in specific yeast mutants correlated with a decreased rate of endocytic patch invagination...

..between mutant alleles of Actin-NonComplementing (ANC) genes and actin (ACT1) or actin-binding protein (SAC6, ABP1, TPM1) genes...

Yeast fimbrin is encoded by the SAC6 gene, mutations of which suppress temperature-sensitive mutations in the actin gene (ACT1)...

..Our studies support a mechanism whereby actin cables serve as "conveyor belts" for retrograde movement and delivery of actin patches/endosomes to FM4-64-labeled internal compartments...

..Thus, the demonstration of an essential link between CBC and spliceosome assembly in vivo indicates that 5' end capping couples pre-mRNA splicing to transcription...

..We theorize that Aip1p-severing activity may involve simultaneous binding to two actin subunits with cofilin wedged between the two actin binding sites of the N- and C-terminal propeller domains...

..Thus, we propose that FIM5 regulates actin dynamics and organization during pollen germination and tube growth via stabilizing actin filaments and organizing them into higher-order structures...

..also show synthetic lethality with rho1 and mutations in certain other cytoskeletal genes (ACT1, MYO1, MYO2, and SAC6) but not with mutations in several noncytoskeletal genes...

..Furthermore, these data support an active role for Aip1p in promoting actin filament turnover...

..However, we reveal that scp1 deletion is compensated for by up-regulation of Sac6. Furthermore, Scp1 levels are increased in the absence of sac6...

..This linkage group identifies a new gene SAC6, whose product, by several genetic criteria, is likely to interact intimately with actin...

Yeast fimbrin is encoded by the SAC6 gene, mutations of which suppress temperature-sensitive mutations in the actin gene (ACT1)...

..Therefore, Scd5p and clathrin are important for actin organization and endocytosis, and Sla2p may provide a critical link between clathrin and the actin cytoskeleton in yeast, similar to HIP1(R) in animal cells...

..The others represent known endocytosis (rvs167 and sac6) and vacuolar protein sorting (vps41) mutants...

..Collectively, this work demonstrates that actin plays a central role in fungal dimorphism...

..Analysis of the cables in these double-mutant cells supports a role for fimbrin in organizing cytoplasmic cables and for Mdm20p and tropomyosin in excluding cofilin from the cables...

..However, the ability to respond to such perturbations by delaying cell cycle progression was restricted to a narrow window of the cell cycle, delimited by the periodic accumulation of the checkpoint effector, Swe1p...

..Furthermore, the deletion of SJL1 suppresses the temperature-sensitive growth defect of sac6, a mutant in yeast fimbrin, supporting a role for synaptojanin family members in actin function...

..In addition, synthetic growth defects were observed between null alleles of GCS1 and SAC6, the gene encoding the yeast fimbrin homologue...

..mutations suppress the defect in cytoskeletal organization and cell morphology seen in ACT1 cells that overexpress SAC6. These findings indicate that the lethal phenotype caused by Sac6p overexpression is mediated through interaction ..

..coding for proteins associated with the cytoskeleton of Saccharomyces cerevisiae: TPM1 coding for tropomyosin, SAC6 for fimbrin and CIN1 for a microtubule-associated protein...

..of cells with either mutation alone indicates a synthetic lethal relationship between this actin allele and the SAC6 gene...

..A null mutation of the actin gene (ACT1) is lethal, but null mutations in the tropomyosin (TPM1), fimbrin (SAC6), Abp1p (ABP1), and capping protein (CAP1 and CAP2) genes have relatively mild or no effects...

..A null mutation of MTI1 exhibited synthetic lethal phenotypes with mutations in SAC6 and SLA2, which encode actin-bundling and cortical actin-binding proteins, respectively...

..It is considered as crucial structural cell wall component since in baker's yeast the lack of CCW12 results in severe cell wall damage and reduced mating efficiency...