UNIPROT #

P27986

PROTEIN NAME

PI3-kinase p85 subunit alpha

SYNONYMS

GRB1 antibody; p85 alpha antibody; p85 antibody; P85A_HUMAN antibody; Phosphatidylinositol 3 kinase associated p 85 alpha antibody; Phosphatidylinositol 3 kinase regulatory 1 antibody; Phosphatidylinositol 3 kinase, regulatory subunit, polypeptide 1 (p85 alpha) antibody; Phosphatidylinositol 3-kinase 85 kDa regulatory subunit alpha antibody; Phosphatidylinositol 3-kinase regulatory subunit alpha antibody; Phosphoinositide 3 kinase, regulatory subunit 1 (alpha) antibody; PI3 kinase p85 subunit alpha antibody; PI3-kinase regulatory subunit alpha antibody; PI3-kinase subunit p85-alpha antibody; PI3K antibody; PI3K regulatory subunit alpha antibody; Pik3r1 antibody; PtdIns 3 kinase p85 alpha antibody; PtdIns-3-kinase regulatory subunit alpha antibody; PtdIns-3-kinase regulatory subunit p85-alpha antibody

SEQUENCE SIMILARITIES

Belongs to the PI3K p85 subunit family.

TISSUE SPECIFICITY

Isoform 2 is expressed in skeletal muscle and brain, and at lower levels in kidney and cardiac muscle. Isoform 2 and isoform 4 are present in skeletal muscle (at protein level).

POST-TRANSLATIONAL MODIFICATION

Polyubiquitinated in T-cells by CBLB; which does not promote proteasomal degradation but impairs association with CD28 and CD3Z upon T-cell activation.; Phosphorylated. Tyrosine phosphorylated in response to signaling by FGFR1, FGFR2, FGFR3 and FGFR4. Phosphorylated by CSF1R. Phosphorylated by ERBB4. Phosphorylated on tyrosine residues by TEK/TIE2. Dephosphorylated by PTPRJ. Phosphorylated by PIK3CA at Ser-608; phosphorylation is stimulated by insulin and PDGF. The relevance of phosphorylation by PIK3CA is however unclear (By similarity). Phosphorylated in response to KIT and KITLG/SCF. Phosphorylated by FGR.

SUBCELLULAR LOCATION

Cytosol. Endoplasmic reticulum. Golgi apparatus. Nucleus. Plasma Membrane.

FUNCTION

Phosphatidylinositol 3-kinase (PI 3-kinase) is composed of p85 and p110 subunits. p85 lacks PI 3-kinase activity and acts as an adapter, coupling p110 to activated protein tyrosine kinase. Two forms of p85 have been described (p85α and p85β), each possessing one SH3 and two SH2 domains. Various p110 isoforms have been identified. p110α and p110β interact with p85α, and p110α has also been shown to interact with p85β in vitro. p110δ expression is restricted to white blood cells. It has been shown to bind p85α and β, but it apparently does not phosphorylate these subunits. p110δ seems to have the capacity to autophosphorylate. p110γ does not interact with the p85 subunits. It has been shown to be activated by α and βγ heterotrimeric G proteins.