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A Ca2+-activated NADPH Oxidase in Testis, Spleen, and Lymph Nodes
Journal article   Open access   Peer reviewed

A Ca2+-activated NADPH Oxidase in Testis, Spleen, and Lymph Nodes

Botond Bánfi, Gergely Molnár, Andres Maturana, Klaus Steger, Balázs Hegedûs, Nicolas Demaurex and Karl-Heinz Krause
The Journal of biological chemistry, Vol.276(40), pp.37594-37601
10/05/2001
DOI: 10.1074/jbc.M103034200
PMID: 11483596
url
https://doi.org/10.1074/jbc.M103034200View
Published (Version of record) Open Access

Abstract

Superoxide and its derivatives are increasingly implicated in the regulation of physiological functions from oxygen sensing and blood pressure regulation to lymphocyte activation and sperm-oocyte fusion. Here we describe a novel superoxide-generating NADPH oxidase referred to as NADPH oxidase 5 (NOX5). NOX5 is distantly related to the gp91phox subunit of the phagocyte NADPH oxidase with conserved regions crucial for the electron transport (NADPH, FAD and heme binding sites). However, NOX5 has a unique N-terminal extension that contains three EF hand motifs. The mRNA of NOX5 is expressed in pachytene spermatocytes of testis and in B- and T-lymphocyte-rich areas of spleen and lymph nodes. When heterologously expressed, NOX5 was quiescent in unstimulated cells. However, in response to elevations of the cytosolic Ca2+concentration it generated large amounts of superoxide. Upon Ca2+ activation, NOX5 also displayed a second function: it became a proton channel, presumably to compensate charge and pH alterations due to electron export. In summary, we have identified a novel NADPH oxidase that generates superoxide and functions as a H+ channel in a Ca2+-dependent manner. NOX5 is likely to be involved in Ca2+-activated, redox-dependent processes of spermatozoa and lymphocytes such as sperm-oocyte fusion, cell proliferation, and cytokine secretion.

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