The function of Ensembl gene identifier ENSG00000138722 (MMRN1, multimerin 1) is as follows. Carrier protein for platelet (but not plasma) factor V/Va. Plays a role in the storage and stabilization of factor V in platelets. Upon release following platelet activation, may limit platelet and plasma factor Va-dependent thrombin generation. Ligand for integrin alpha-IIb/beta-3 and integrin alpha-V/beta-3 on activated platelets, and may function as an extracellular matrix or adhesive protein. {ECO:0000269|PubMed:16363244, ECO:0000269|PubMed:19132231, ECO:0000269|PubMed:7629143}.