Osteosarcoma Amplified 9 (OS9)

Protein OS-9 is a protein that is highly expressed in osteosarcomas.This protein binds to the hypoxia-inducible factor 1 (HIF-1), a key regulator of the hypoxic response and angiogenesis, and promotes the degradation of one of its subunits. Alternate transcriptional splice variants, encoding different isoforms, have been characterized.

The deduced 667-amino acid protein has a calculated molecular mass of 75.6 kD. OS9 contains an N-terminal leader peptide, a 211-amino acid hydrophilic region with 8 cysteines, and an acidic region with multiple predicted hydrophilic helices. It also has a putative nuclear targeting signal. The hydrophilic region of OS9 is highly conserved in human, S. cerevisiae, and C. elegans, with complete conservation of the 8 cysteines.