Transmembrane Glycoprotein NMB (GPNMB)

GPNMB is a type I transmembrane glycoprotein which shows homology to the pmel17 precursor, a melanocyte-specific protein.GPNMB has been reported to be expressed in various cell types, including: melanocytes, osteoclasts, osteoblasts, dendritic cells, and it is overexpressed in various cancer types. In melanocytic cells and osteoclasts the GPNMB gene is transcritionally regulated by Microphthalmia-associated transcription factor. In osteoblast progenitor cells, Osteoactivin is induced by BMP-2 in a SMAD1 dependent manner to promote osteoblast differentiation. Similarly, Osteoactivin expression increases during osteoclast differentiation and it is functionally implicated in this process, possibly by promoting the fusion of osteoclast progenitor cells.