Sperm Associated Antigen 9 (SPAG9)

Extracellular signals are transduced into cells through mitogen-activated protein kinases. The structural organization of these kinases into specific signaling domains is facilitated by scaffolding proteins involved in closely tethering different kinases so that successive phosphorylation events can occur.

Sperm Associated Antigen 9 is a scaffolding protein that brings together mitogen-activated protein kinases and their transcription factor targets for the activation of specific signaling pathways. This gene which is abundantly expressed in testicular haploid germ cells encodes a protein that is recognized by sperm-agglutinating antibodies and implicated in infertility.Alternatively spliced transcript variants encoding different isoforms have been found for this gene.