| ex-hormone binding globulin (SHBG) and corticosteroid binding globulin (CBG) are the major plasma transport proteins for sex-steroids and glucocorticoids, respectively, and may impact directly upon steroid hormone bioavailability to target cells. Androgen binding protein (ABP) is closely related to SHBG and is believed to maintain an androgenic environment for sperm maturation. The isolation of SHBG-related cDNAs from human testis and a corresponding transcription unit indicates that SHBG and ABP are encoded by the same gene. In addition, the SHBG/ABP gene gives rise to two novel testicular transcripts through a process of alternative splicing. The putative proteins encoded by these transcripts are related to SHBG, but contain differences that may specify unique functions. Interestingly, the human SHBG/ABP gene contains multiple Alu repetitive elements, and one of these was implicated in the process of alternative splicing. It is clear that CBG is a member of the serine proteinase inhibitor superfamily, and is closely related to... |
