Homologous proteins hormones

HMG CoA-Reductase HMG-CoA-Reductase Inhibitors Homologous Desensitization Homologous Proteins Homologous Recombination Homology Modeling Hormonal Contraceptives Hormone Replacement Therapy (HRT)... 

For protein hormones where there was less sequence homology with the equivalent bovine or porcine protein, supplies for clinical use were derived directly from human tissues. Somatotropin or growth hormone (GH) was purihed from cadaver pituitaries. The limitations on GH use were due to its scarcity, which is well described in a review by Frasier [1]. Other peptide hormones purihed from human sources... 

Pituitary prolactin is a protein hormone comprising a single polypeptide chain of about 200 amino acid residues and 3 intrachain disulphide bridges [1,2]. It is structurally homologous with growth hormone (GH) as is discussed in Chapter 13 (Fig. 1). Amino acid sequences of prolactins from various different species have been described [1-3] they show a considerable amount of species variation, which is most notable in the case of the prolactins of the rat and mouse, which differ from prolactins of other mammals at about 40% of all amino acid residues [3,4]. 

The members of the cytosolic hormone receptor family are homologous proteins and the mechanism of action involves translocation of the receptor with hormone bound to the nucleus, where it homodimerizes (or heterodimerizes with related activated receptors) and binds to specific promoters to switch on transcription of particular genes. The ultimate response to the hormonal stimulus is expression of particular proteins that variously influence development and metabolism as briefly outlined below. 

The most valuable confirmation of this view to date is, without doubt, to be found in the known structures of homologous proteins and peptide hormones, that is compounds of identical biological function isolated from different species. As is well known, the primary structures of the homologous insulins, corticotropins, hypertensins, posterior pituitary hormones, and heme peptide sequences from cytochromes c are closely similar and differ only at certain definite sites in the peptide chains. These can, in particular, serve as a useful point of departure in a search for more general principles governing protein structure, and in the comparison of different proteins. 

As the molecular masses and amino acid sequences of the protein hormones increase, the cross-reactivity of antisera in the different species becomes more problematic, and homologous antisera are required (Miller and Valdes 1992 Valdes and Miller 1992). Several homologous reagents are commercially available (e.g., prolactin, thyrotrophin, luteotrophin, and follitrophin for rats, and canine thyrotrophin). Some very specialized centers are able to produce suitable antisera given purified hormones, but this is a time-consuming process and the majority of toxicology laboratories use antisera from external suppliers who often can provide information on cross-reactivity. 

Growth-Arrest-Specific protein 2 Domain Gastrin/cholecystokinin/caerulein family Dynamin GTPase effector domain Gelsolin homology domain G protein y subunit-like motifs Glycoprotein hormone a chain homologs... 

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