[Hormone receptors and hormone action (author's transl)].
All hormones act only on their target tissues. The ability of a tissue to react to a hormone is due to the presence of a receptor in or at the cell. There are two classes of hormone receptors: those bound to the membrane and those present in the cytosol. Peptide hormones generally act through membrane receptors. The interaction of a hormone with its receptors leads to an activation of the adenylate cyclase and the production of cyclo-AMP, the second messenger. In cases where several hormones act on the same tissue (example: adipose tissue) they must interact with their specific receptors, but presumably with the same adenylate cyclase. This interaction is discussed. The receptors for steroid hormones are not membrane-bound, but present in the cytosol. They are specific proteins which bind the hormone rather tightly. This results in a change in protein conformation, sometimes accompanied by a dimerization; the modified receptor is then transferred to the cell nucleus where it stimulates transcription. The control mechanisms of transcription are discussed; the most probable mode of action is removal of a repressor or repressor-like component from chromatin which results in deinhibition of transcription. mRNA is then produced and translated into protein. Post-transcriptional controls have been postulated, but never unequivocally demonstrated.
D000262:Adenylyl Cyclases / Q000378:metabolism; D002462:Cell Membrane; D002843:Chromatin / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D003600:Cytosol; D006728:Hormones / Q000502:physiology*; D006801:Humans; D011487:Protein Conformation; D012333:RNA, Messenger / Q000096:biosynthesis; D011956:Receptors, Cell Surface / Q000502:physiology*; D014158:Transcription, Genetic
D002843:Chromatin; D006728:Hormones; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D000242:Cyclic AMP; D000262:Adenylyl Cyclases
Hormonrezeptoren und Hormonwirkung.