Src kinase-associated phosphoprotein 1 (src family-associated phosphoprotein 1, src kinase-associated phosphoprotein of 55 kD, pp55, SKAP-55, SKAP1, SCAP1, SKAP55)
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Function
- positively regulates T-cell receptor signaling by enhancing the MAP kinase pathway
- required for optimal conjugation between T-cells & antigen- presenting cells by promoting clustering of integrin ITGAL on the surface of T-cells
- role in high affinity immunoglobulin epsilon receptor signaling in mast cells (putative)
- interacts with FYN & PTPRC
- phosphorylated on Tyr
- interacts with GRB2 when phosphorylated on Tyr-271 by FYN
- Tyr-232 is dephosphorylated by PTPRC
- interacts with FYB via SH3 domain, required for SKAP2 protein stability
- phosphorylation by FYN on Tyr-295 abolishes interaction with FYB
- component of complex consisting of SKAP1, FYB & CLNK
Structure
- homodimer
- belongs to the SKAP family
- contains 1 PH domain
- contains 1 SH3 domain, interacts with FYB
Compartment
- cytoplasm nucleus
- upon T-cell stimulation, translocates to lipid rafts at the cell membrane
Alternative splicing
named isoforms=2
Expression
- highly expressed in thymocytes & peripheral blood lymphocytes
- also expressed in spleen cells & testis
- present in T-cells (at protein level)