Transcription factor that binds to DNA at the consensus sequence 5'-AACAAT-3' (PubMed:10871192). Binds to the proximal promoter region of the myelin protein MPZ gene, and may thereby be involved in the differentiation of oligodendroglia in the developing spinal tube (By similarity). Binds to the gene promoter of MBP and acts as a transcriptional repressor (By similarity). Binds to and modifies the activity of TCF7/TCF1, thereby inhibiting transcription and modulates normal gamma-delta T-cell development and differentiation of IL17A expressing gamma-delta T-cells (By similarity). Regulates expression of BLK in the differentiation of IL17A expressing gamma-delta T-cells (By similarity). Promotes brown adipocyte differentiation (By similarity). Inhibitor of WNT signaling (PubMed:20028982). {ECO:0000250|UniProtKB:Q04891, ECO:0000269|PubMed:10871192, ECO:0000269|PubMed:20028982}. This is the function of SOX13 (SRY-box transcription factor 13, ENSG00000143842).