Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Molecular mechanisms regulating the binding, amphipathic stabilization, and metabolism of the major neutral lipids (e.g., cholesteryl esters, triglycerides, and fatty acids) are well studied, but the details of their movement from a binding compartment to a metabolic compartment deserve further attention. Since all neutral lipids must cross hydrophilic segments of plasma membranes during such movement, we postulate that a critical receptor-like site exists on the plasma membrane to mediate a step between binding and metabolism and that membrane-associated heparin is a key part of this mediator. For example, intestinal brush border membranes containing heparin bind homogeneous human pancreatic 125I-labeled cholesterol esterase (100 kDa) and 125I-labeled triglyceride lipase (52 kDa). This interaction is enzyme concentration-dependent, specific, and saturable and is reversed upon addition of soluble heparin. Scatchard analysis demonstrates a single class of receptors with a Kd of 100 nM and a Bmax of approximately 50-60 pmol per mg of vesicle protein. In contrast, enzymes associated with the hydrolysis of hydrophilic compounds such as amylase, phospholipase A2, and deoxyribonuclease do not bind to intestinal membranes in this manner. Human pancreatic cholesterol esterase also binds specifically and saturably to cultured intestinal epithelial cells (CaCo-2), and soluble heparin significantly diminishes the cellular uptake of the resultant hydrophobic reaction products (cholesterol and free fatty acids). We conclude that a physiological role for intestinal heparin is that of a mediator to bind neutral lipolytic enzymes at the brush border and thus promote absorption of the subsequent hydrolyzed nutrients in the intestine. This mechanism may be a generalizable pathway for transport of neutral lipids into endothelial and other cells.
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PMID:Receptor-like function of heparin in the binding and uptake of neutral lipids. 317 44

Testosterone-treated calf thymocytes produce increased amounts of proteins, termed lipokinins, that stimulate phospholipase A2 from snake venom and mammalian tissue. The induction of these proteins by testosterone is blocked by cycloheximide and, thus, requires new protein synthesis. These proteins activate phospholipase A2 stoichiometrically. They are inactivated by boiling, trypsin or alkaline phosphatase but not by deoxyribonuclease or ribonuclease. Lipokinins significantly repair the failure of masculinization in the Tfm mouse with an X-linked deficiency of androgen-receptor. Thus, the post-receptor effects of testosterone on embryonic genitalia may be mediated through stimulation of phospholipase A2 by lipokinins. Moreover, lipokinins may be involved as stimulators of the arachidonic acid cascade, as lipocortins are inhibitors.
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PMID:John Lattimer lecture. Lipokinins: novel phospholipase A2 activators mediate testosterone effects on embryonic genitalia. 318 94