May be involved in G protein-linked signaling. Interacts with GLUT1 (C-terminus), ACTN1, KIF1B, MYO6, PLEKHG5, SDC4/syndecan-4 and SEMA4C/semaphorin-4C (By similarity). Interacts with RGS19 C-terminus. Interacts with HTLV-I Tax through the PDZ domain. Widely expressed (PubMed:9770488). Expressed in skeletal muscle (at protein level) (PubMed:32413282). The disease may be caused by variants affecting the gene represented in this entry. GGC repeat expansions in the 5'-UTR ranging from 73 to 164 were reported in patients, compared with a normal range from 12 to 32 in unaffected individuals. Patient skeletal muscle showed similar protein levels to those of unaffected individuals. Belongs to the GIPC family.