title: MOde of entry of steroid and thyroid hormones into cells.
abstract: Characteristics of the processes by which steroid and thyroid hormones enter tissues, cells and membrane vesicles are reviewed. Several authors suggest that entry is by passive diffusion: the accumulation within cells is attributed to cytoplasmic binding proteins. Other authors, however, propose a membrane-mediated process of entry. The involvement of saturability, high specificity, sensitivity to temperature, sulfhydryl and cell-surface-perturbing reagents and hydrolytic enzymes support the latter view. Purified plasma-membrane vesicle preparations retain several characteristics of entry shown by intact cells. Intracellular hormone-binding protein would not contribute to processes observed with these preparations.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane; D004058:Diffusion; D005260:Female; D006728:Hormones / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D051381:Rats; D013256:Steroids / Q000378:metabolism*; D013963:Thyroid Hormones / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D006728:Hormones; D013256:Steroids; D013963:Thyroid Hormones