Phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1)

Phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1) is a ubiquitously expressed transmembrane adaptor protein found in lipid rafts of the plasma membrane.[2][3][4][5][6] PAG1 binds cytoplasmic C-terminal Src kinase (Csk) and other Src family kinases (SFKs), acting as a negative regulator of SFK-mediated signaling in immune cells, especially T cells and mast cells.[2][3][5][6] PAG1 contains multiple tyrosine phosphorylation sites and interacts with kinases such as Fyn, Lck, Lyn, and Src, as well as signaling effectors including PI3K, Shc, and Vav.[2][3] Its phosphorylation recruits Csk to lipid rafts, where Csk inhibits SFK activity, providing a feedback mechanism for modulation of receptor-mediated signaling, particularly in TCR and FcεRI pathways.[2][3][4][5][6] PAG1 also contributes to the regulation of cell adhesion and cytoskeletal organization and has been linked to roles in cancer cell biology and leukemias.[2][5] No specific drugs are known to target PAG1 directly, but its regulatory role in key signaling pathways makes it relevant as a potential biomarker or target for future therapeutic strategies.[2][5][6]

Other names

Csk-binding proteinCBPPAGTransmembrane adaptor protein PAGTransmembrane phosphoprotein CbpPAG1

No known mechanism of action for drugs, as PAG1 itself is not a direct drug target; it functions as a regulatory adaptor, especially for kinase signaling.