Glypican-1

Glypican-1 (GPC1) is a cell surface heparan sulfate proteoglycan that functions as a co-factor in multiple signaling pathways (UniProt: P35052). Via its heparan sulfate side chains, it binds alpha-4(V) collagen and regulates FGF2 sequestration in lipid rafts, thereby modulating skeletal muscle differentiation and myelin formation. The protein may also facilitate prion protein conversion by promoting interaction between PRPN(C) and PRNP(Sc) forms.

Glypican-1 is expressed broadly across tissues and has been implicated in neurological processes including myelination and prion-related pathology. While no disease associations are documented in UniProt records, the protein's involvement in lipid raft biology and growth factor signaling suggests relevance to neurodegenerative mechanisms.

In Alzheimer's disease, glypican-1 is significantly downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The protein showed a mean log2 fold-change of −0.458 across subcellular fractions in TMT-labeled tandem mass spectrometry analysis. This downregulation may impair heparan sulfate-mediated signaling and cellular homeostasis in AD pathology.