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. Multimeric. Composed of varying sized, disulfide-linked multimers, the smallest of which is a homotrimer. Proteolysis of the promultimerin in the N-terminal region, leads to the mature p155 form that is stored in platelets. Interacts with factor V/Va. Synthesized by endothelial cells and megakaryocytes. Stored in platelet alpha granules and endothelial cell Weibel-Palade bodies, following activation of these cells, it is released and attached to megakaryocytes, platelets, endothelium and subendothelium of blood vessels. Not found in plasma. Found in vascular tissues such as placenta, lung, and liver. The N-terminus is blocked. Extensively N-glycosylated. Deficiency in multimerin-1 due to proteolytic degradation within the platelet alpha granules is associated with an autosomal dominant bleeding disorder (factor V Quebec).