SEX HORMONE BINDING GLOBULIN AND STEROID SIGNALING AT THE CELL MEMBRANE

Sex hormone-binding globulin (SHBG) both regulates the free concentration of certain steroids in plasma and participates in a cellular steroid signaling pathway originating at the cell membrane. The biochemistry of SHBG-mediated steroid signaling has been described in some detail. It is clear that it is a system that is distinct from steroid signaling through classical nuclear steroid hormone receptors. We will summarize the initial steps of steroid signaling through SHBG and discuss biologic events that are attributed to, or are speculated to have SHBG-mediated steroid signaling as their basis. Finally, we talk about the local expression of SHBG in target tissues and its implications for the regulation of cellular steroid signaling.