The tissue source and cellular control of the apparent size of androgen binding protein (Abp), a mouse salivary protein whose electrophoretic mobility is under the control of sex-limited saliva pattern (Ssp).

Expression of the dominant allele, Ssps, at the Sex-limited saliva pattern locus in mice results in an alteration of the electrophoretic mobility of a mouse salivary protein from the F (fast) to the S (slow) type [Karn, R.C., et al. (1980). Genetics 94:s52; Karn, R.C., et al. (1982). Biochem. Genet. 20:493]. We now demonstrate that the protein affected binds androgen and has a basic heterodimeric structure with the subunits connected by disulfide bridging. It is produced in the submaxillary gland where the alteration takes place. The change in electrophoretic mobility from F to S appears to be primarily the result of an increase in the molecular weight of the larger subunit since the isoelectric point changes very little. We discuss the possible causes of the increase in molecular weight.