The SRY protein, like HMG 1, recognizes (CA)n sequences, an abundant repeat sequence in vertebrates.

The sex-determining region of the Y chromosome gene, sry is expressed in the foetal mouse for a brief period, just before testis differentiation, which could be consistent with negative autoregulation. SRY is a DNA binding protein which can bind to cruciform DNA and to linear DNA with a sequence specificity. We have examined if the Sry gene contain DNA binding sites for the SRY protein itself. We have found that in an in vitro assay, the SRY protein binds to several sites of the Sry gene and especially to a (CA)25 sequence and to a (CAG)30 repeat. These binding suggest that the function of SRY and in a general way HMG-box proteins may be mediated by an interaction with repeat sequences.