C-terminal, alpha helical domain of Metaxin and related proteins
Glutathione S-transferase (GST) C-terminal domain family, Metaxin subfamily; composed of metaxins and related proteins. Metaxin 1 is a component of a preprotein import complex of the mitochondrial outer membrane. It extends to the cytosol and is anchored to the mitochondrial membrane through its C-terminal domain. In mice, metaxin is required for embryonic development. In humans, alterations in the metaxin gene may be associated with Gaucher disease. Metaxin 2 binds to metaxin 1 and may also play a role in protein translocation into the mitochondria. Genome sequencing shows that a third metaxin gene also exists in zebrafish, Xenopus, chicken, and mammals. Sequence analysis suggests that all three metaxins share a common ancestry and that they possess similarity to GSTs. Also included in the subfamily are uncharacterized proteins with similarity to metaxins, including a novel GST from Rhodococcus with toluene o-monooxygenase and glutamylcysteine synthetase activities. Other members are the cadmium-inducible lysosomal protein CDR-1 and its homologs from C. elegans, and the failed axon connections (fax) protein from Drosophila. CDR-1 is an integral membrane protein that functions to protect against cadmium toxicity and may also have a role in osmoregulation to maintain salt balance in C. elegans. The fax gene of Drosophila was identified as a genetic modifier of Abelson (Abl) tyrosine kinase. The fax protein is localized in cellular membranes and is expressed in embryonic mesoderm and axons of the central nervous system.