This gene is predominantly expressed in the testis and lymphocyte-rich areas of spleen and lymph nodes. It encodes a calcium-dependen NADPH oxidase that generates superoxide, and functions as a calcium-dependent proton channel that may regulate redox-dependent processes in lymphocytes and spermatozoa. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Oct 2011].