Vps8 is one of the Golgi complex components necessary for vacuolar sorting []. Eukaryotic cells contain a highly dynamic endo-membrane system, in which individual organelles keep their identity despite continuous vesicle generation and fusion. Vesicles that bud from a donor membrane are targeted and delivered to each individual organelle, where they release their cargo after fusion with the acceptor membrane. Vps8 is the core component of the endosomal tethering complex CORVET (class C core vacuole/endosome tethering). Vps8 co-operates with Vps21-GTP to mediate endosomal clustering in a reaction that is dependent on Vps3. Vps8 is the only CORVET subunit that is enriched on late endosomes, suggesting that it is a marker for the maturation of late endosomes. Late endosomes form intralumenal vesicles, and the resulting multivesicular bodies fuse with the vacuole to release their cargoes [].This entry represents the central domain of Vps8.
This entry includes Vps41 and Vps8.Vps41 is a subunit of the homotypic vacuole fusion and vacuole protein sorting (HOPS) complex; essential for membrane docking and fusion at the Golgi-to-endosome and endosome-to-vacuole stages of protein transport [, , ].Vps8 is one of the Golgi complex components necessary for vacuolar sorting []. Eukaryotic cells contain a highly dynamic endomembrane system, in which individual organelles keep their identity despite continuous vesicle generation and fusion. Vesicles that bud from a donor membrane are targeted and delivered to each individual organelle, where they release their cargo after fusion with the acceptor membrane. Vps8 is the core component of the endosomal tethering complex CORVET (class C core vacuole/endosome tethering). Vps8 co-operates with Vps21-GTP to mediate endosomal clustering in a reaction that is dependent on Vps3. Vps8 is the only CORVET subunit that is enriched on late endosomes, suggesting that it is a marker for the maturation of late endosomes. Late endosomes form intraluminal vesicles, and the resulting multivesicular bodies fuse with the vacuole to release their cargoes [].
Clathrin is a triskelion-shaped cytoplasmic protein that polymerises into a polyhedral lattice on intracellular membranes to form protein-coated membrane vesicles. Lattice formation induces the sorting of membrane proteins during endocytosis and organelle biogenesis by interacting with membrane-associated adaptor molecules. Clathrin functions as a trimer, and these trimers, or triskelions, are comprised of three legs joined by a central vertex. Each leg consists of one heavy chain and one light chain. The clathrin heavy-chain contains a 145-residue repeat that is present in seven copies [, ]. The clathrin heavy-chain repeat (CHCR) is also found in nonclathrin proteins such as Pep3, Pep5, Vam6, Vps41, and Vps8 from Saccharomyces cerevisiae and their orthologs from other eukaryotes [, , , ]. These proteins, like clathrins, are involved in vacuolar maintenance and protein sorting. The CHCR repeats in these proteins could mediate protein-protein interactions, or possibly represent clathrin-binding domains, or perform clathrin-like functions. CHCR repeats in the clathrin heavy chain, Saccharomyces cerevisiae Vamp2 and human Vamp6 have been implicated in homooligomerization, suggesting that this may be the primary function of this repeat.The CHCR repeat folds into an elongated right-handed superhelix coil of short α-helices []. Individual 'helix-turn-helix-loop' or helix hairpin units comprise the canonical repeat and stack along the superhelix axis to form a single extended domain. The canonical hairpin repeat of the clathrin superhelix resembles a tetratrico peptide repeat (TPR), but is shorter and lacks the characteristic spacing of the hydrophobic residues in TPRs.
