Sex-hormonal regulation of 20.5 and 24 kDa major male-specific proteins in Syrian hamster submandibular gland.

Examination of SDS-PAGE protein profiles of adult hamster submandibular glands revealed a marked sexual dimorphism in levels of 20.5 and 24 kDa proteins. These proteins, together apparently constituting 40% of soluble proteins, were present in intact and castrated males but not in females. This sexual dimorphism was also confirmed in two-dimensional gels which revealed that the protein at 24 kDa was heterogenous and consisted of at least four species. In females, ovariectomy induced the 20.5 and 24 kDa proteins to male levels. Estrogen administration to gonadectomized hamsters of either sex or to intact males obliterated these proteins. Whereas androgens had no effect in males, they markedly inhibited these proteins in ovariectomized females. Androgens were less potent than estrogens in this regard. Progesterone or dexamethasone had no effect on these proteins. Only male saliva contained 20.5 and 24 kDa major proteins. These submandibular male-specific proteins are useful markers to study the hormonal regulation of this gland, and they provide a model system to study how both androgens and estrogens mediate inhibition of protein synthesis. The possible functions of these submandibular male-specific proteins are discussed.