Difference between revisions of "Phosphatase Subfamily STS"

Revision as of 04:47, 3 January 2015

Phosphatase Classification: Fold HP: Superfamily HP (histidine phosphatase): HP, branch1 family: Subfamily STS

Evolution

STS subfamily is found in most metazoan. Human has two STSs: STS-1 (TULA-2 or UBASH3B) and STS-2 (TULA-1 or UBASH3A). STS-2 is present in lobe-finned fish, birds and mammals, but not other bony fishes. STS-1 emerged earlier than STS-2, which is found in most metazoan, from sponge to nematodes, insects, fishes, birds, and mammals.

Domain

STS has three domains: UBA, SH3 and HP2 phosphatase domain.

Functions

Human STS-1 and STS-2 are involved in T Cell Receptor Signaling Pathways by regulating kinase Syk and ZAP-70, two members of Syk kinase subfamily.

STS-1 decreases tyrosine phosphorylation of Syk in vivo and in vitro [1, 2]. Inactivated STS-1 increases tyrosine phosphorylation of Syk in cells co-transfected to overexpress these proteins, thus acting as a dominant-negative form that suppresses dephosphorylation of Syk caused by endogenous STS-1. However, the same assay on STS-2 shows the phosphatase activity of STS-2 is negligible compared to STS-1 [3]. In addition, both STS-1 and STS-2 regulates kinase ZAP-70 activation [2].

Human STS-1 can also dephosphorylate phospho-tyrosines on EGFR. The histidine phosphatase domain of STS-1, but not of STS-2, dephosphorylates the EGFR at multiple tyrosines, and thereby terminating its signalling and endocytosis [4].

Both human STSs negatively regulate the endocytosis of receptor tyrosine kinases. The UBA domain of STS-2 and SH3-dependent Cbl-binding are required for this function. STS-2 is predominantly in naive and mature T cells , whereas STS-1 is expressed ubiquitously.

References

1. Error fetching PMID 20670933: [chen10]
2. Error fetching PMID 14738763: [carpino04]
3. Error fetching PMID 18189269: [STS_2]
4. Error fetching PMID 17880946: [STS_1]