Modulates calcium-dependent activity of inositol 1,4,5- triphosphate receptors (ITPRs) (PubMed:14570872). Inhibits agonist- induced intracellular calcium signaling (PubMed:15980432). Enhances inactivation and does not support calcium-dependent facilitation of voltage-dependent P/Q-type calcium channels (PubMed:11865310). Causes calcium-dependent facilitation and inhibits inactivation of L-type calcium channels by binding to the same sites as calmodulin in the C- terminal domain of CACNA1C, but has an opposite effect on channel function (PubMed:15140941). Suppresses the calcium-dependent inactivation of CACNA1D (By similarity). Inhibits TRPC5 channels (PubMed:15895247). Prevents NMDA receptor-induced cellular degeneration. Required for the normal transfer of light signals through the retina (By similarity). {ECO:0000250|UniProtKB:O88751, ECO:0000250|UniProtKB:Q9JLK7, ECO:0000269|PubMed:11865310, ECO:0000269|PubMed:14570872, ECO:0000269|PubMed:15140941, ECO:0000269|PubMed:15895247, ECO:0000269|PubMed:15980432}. This is the function of CABP1 (calcium binding protein 1, Ensembl gene identifier ENSG00000157782).