High impact information on SEC6

• We show that Sec6/8 homologs are components of a cytosolic, approximately 17S complex in nonpolarized MDCK epithelial cells [1].
• Sec6/8 complex is recruited to cell-cell contacts and specifies transport vesicle delivery to the basal-lateral membrane in epithelial cells [1].
• In budding yeast, the Sec6/8p complex is essential for generating cell polarity by specifying vesicle delivery to the bud tip [1].
• These results indicate that lateral membrane recruitment of the Sec6/8 complex is a consequence of cell-cell adhesion and is essential for the biogenesis of epithelial cell surface polarity [1].
• Targeting vesicles to specific sites on the plasma membrane: the role of the sec6/8 complex [2].

Biological context of SEC6

• Previously, we have shown that three of these genes, SEC6, SEC8 and SEC15, encode components of a multisubunit complex which localizes to the tip of the bud, the predominant site of exocytosis in S. cerevisiae [3].
• This study shows that the single point mutation L633P in the SEC6 coding region defines the sec6-4 phenotype [4].
• Gene disruption and marker rescue experiments indicate that SEC6 is a single copy gene essential for growth [5].

Anatomical context of SEC6

• The SEC6 gene encodes a protein required for an event leading to fusion of post-Golgi vesicles with the plasma membrane in Saccharomyces cerevisiae cells [5].
• Moreover, these sac1 suppressor properties also extended to sec6 and sec9 secretory vesicle defects [6].
• Rho1p comigrated with post-Golgi transport vesicles during fractionation of P3 organelles from wild-type or sec6 cells [7].
• Green fluorescent protein (GFP)-fusions of nearly every subunit of the mammalian Sec6/8 complex were expressed in Madin-Darby canine kidney (MDCK) cells, but they failed to assemble into a complex with endogenous proteins and localized in the cytosol [8].
• However, in chc1/sec6 double mutants, CPY-GFP is present in internal structures, possibly endosomal membranes, that do not colocalize with the vacuole [9].

Associations of SEC6 with chemical compounds

• Sec6 cofractionates with Sec8/15 by immobilized metal affinity chromatography, gel filtration chromatography, and by sucrose velocity centrifugation [10].
• Here, we examined the role of the SEC6-SEC8 (exocyst) complex, implicated in trafficking of secretory vesicles to fusion sites in the plasma membrane in yeast and in regulating glucose-stimulated insulin secretion from pancreatic MIN6 beta cells [11].
• Glutaraldehyde-fixed rat brain sec6/8 complex adopts a conformation resembling the letter "T" or "Y". The sec6/8 and septin complexes likely play an important role in trafficking vesicles and organizing proteins at the plasma membrane of neurons [12].

Physical interactions of SEC6

• These data indicate that the Sec8/15 complex contains Sec6 as a stable component [10].

Other interactions of SEC6

• However, loss of sec15 does not cause cell lethality in contrast to loss of sec5 or sec6 [13].
• The late secretory mutants sec1, sec4, and sec6 accumulate both vesicle populations, while neither is detected in wild-type cells, early sec mutants, or a sec13 sec6 double mutant [14].
• Secretory mutants (sec1, sec6) of Saccharomyces cerevisiae accumulate large pools of secretory vesicles at the restrictive temperature (37 degrees C) because of a block in the delivery of vesicles to the cell surface [15].
• Chitinase O-mannosylation was further examined in the temperature-sensitive secretion mutants sec18, sec7, and sec6 [16].
• The chimaeric protein Jen1p-GFP is targeted to the plasma membrane via a Sec6-dependent process; upon treatment with glucose, it is endocytosed via END3 and targeted for degradation in the vacuole [17].

Analytical, diagnostic and therapeutic context of SEC6

• Additional proteins associated with Sec6/8/15 were identified by immunoprecipitations from radiolabeled lysates [10].
• The c-myc-Sec8 protein is localized by immunofluorescence to small bud tips indicating that the Sec6/8/15 complex may function at sites of exocytosis [10].

References