This family of proteins, which contains SH3BGRL3, is functionally uncharacterised. SH3BGRL3 is a highly conserved small protein, which is widely expressed and shows a significant similarity to glutaredoxin 1 (GRX1) of Escherichia coli which is predicted to belong to the thioredoxinsuperfamily. However, SH3BGRL3 lacks both conserved cysteine residues, which characterisethe enzymatic active site of GRX. This structural feature raises the possibility that SH3BGRL3 and its homologues could function asendogenous modulators of GRX activity [].
