Transglutaminase activity arising from Factor XIIIA is required for stabilization and conversion of plasma fibronectin into osteoblast matrix. Detyrosinated Glu-tubulin is a substrate for cellular Factor XIIIA transglutaminase in differentiating osteoblasts. Serotonin (5-HT) inhibits Factor XIII-A mediated plasma fibronectin matrix assembly and crosslinking in osteoblast cultures via direct competition with transamidation. Transglutaminases in bone formation and bone matrix stabilization

In: Transglutaminases: Multiple Functional Modifiers and Targets for New Drug Discovery. Transglutaminases factor XIII-A and TG2 regulate resorption, adipogenesis and plasmafibronectin homeostasis in bone and bone marrow