VPS

VPS may refer to:

Class III PI 3-kinase

Class III PI 3-kinase is a subgroup of the enzyme family, phosphoinositide 3-kinase that share a common protein domain structure, substrate specificity and method of activation.

There is only one known class III PI 3-kinase, Vps34, which is also the only PI 3-kinase expressed in all eukaryotic cells. In humans it is encoded by the PIK3C3 gene. In human cells Vps34 associates with a regulatory subunit, p150.

Substrate specificity

Vps34 is more accurately described as a phosphatylinositol 3-kinase. In vivo Vps34 can phosphorylate only Phosphatidylinositol to form phosphatidylinositol (3)-phosphate (PtdIns(3)P).

Functions

Vps34 was first identified in a Saccharomyces cerevisiae (budding yeast) screen for proteins involved vesicle-mediated vacuolar protein sorting (hence Vps). A number of proteins containing a phosphoinositide binding domain specific for PtdIns(3)P that function in cellular protein trafficking have been identified.

Vps34 has been shown to interact with Vps15, a protein kinase. Vps15 can activate the lipid kinase activity of Vps34 and interact with Rab5, which has been hypothesized to recruit the Vps34/15 complex to early endosomes. Vps15 has a myristoylation tag that associates the complex with the membrane. The Vps34/15 complex also can interact with Rab7. Together, the complex can function at early to late endosomes.

VPS29

VPS29 is a human gene coding for the vacuolar protein sorting protein Vps29, a component of the retromer complex.

Yeast homolog

The homologous protein (one that performs the same function) in yeast is Vacuolar protein sorting 29 homolog (S. cerevisiae).

Function

VPS29 belongs to a group of genes coding for vacuolar protein sorting (VPS) proteins that, when functionally impaired, disrupt the efficient delivery of vacuolar hydrolases. The protein encoded by this gene, Vps29, is a component of a large multimeric complex, termed the retromer complex, which is involved in retrograde transport of proteins from endosomes to the trans-Golgi network. Vps29 may be involved in the formation of the inner shell of the retromer coat for retrograde vesicles leaving the prevacuolar compartment.Alternative splice variants encoding different isoforms, and usage of multiple polyadenylation sites have been found for this gene.

References

Further reading