Glycoprotein hormones protein

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... 

The principal compounds that act as inhibitors of viral protein synthesis are the interferons. These compounds are members of a naturally occurring family of glycoprotein hormones (RMM 20 000-160 000), which are produced by nearly all types of eukaryotic cell. Three general classes of interferons are known to occur naturally in mammals, namely the a-interferons produced by leucocytes, P-interferons produced by fibroblasts and y-interferons produced by T lymphocytes. They form part of the human immune system. It is believed that the presence of virons and pathogens in the body switches on the mRNA that stimulates the production and release of interferons. These interferons are thought to stimulate the production of proteins that inhibit the synthesis of viral mRNA and viral proteins. a-Interferons also enhance the activity of T killer cells. 

After secretion, the hormones circulate in blood for periods ranging from minutes (insulin) to a few hours (glycoprotein hormones). The protein hormones, being water-soluble, circulate in free form and are not bound to specific proteins. Their concentrations in blood are very low, the resting concentrations being 1CT11 M to 10 10 M. Under stimulated conditions the concentrations of peptide hormones in blood may rise 5- to 100-fold. 

Typical biological compounds that are separated by HIC include, cytochrome P-450, enzymes, DNA polymerase, epidermal growth factor, glycoprotein hormones, human immunoglobulins, human recombinant DNA and canine pancreatic juice proteins. Many HIC techniques have been used for large scale purification of proteins. 

Cells that produce peptide, protein, or glycoprotein hormones are derived embryologically from the entoderm or ectoblast (progenitor of ectoderm and neuroectoderm). More than 40 hormones have been identified, containing from three to over 200 amino acid residues. Table 30-2 lists the important hormones and hormonal candidates, number of amino acid residues, and sites of synthesis. 

The clearance of released hormone from the circulation is critical for the regulation of hormone concentration. The rate of clearance may vary from a few minutes for polypeptide hormones, to a few hours for steroid and glycoprotein hormones, to days for thyroid hormones. The peptide hormones are cleared from the circulation mostly by proteolytic mechanisms in lysosomes after their uptake by cells through binding to cell-surface receptors and nonreceptor hormone-binding sites. Steroid hormones are bound to carrier proteins in the blood as mentioned above. Binding to... 

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