Activation of trout adipose tissue lipoprotein lipase by trout apoproteins.
In rainbow trout (Salmo gairdnerii) lipoprotein profiles change during the annual sexual cycle. Among other factors, lipoprotein lipase (LPL) activity might play a role. This enzyme is activated by trout serum suggesting the existence of a cofactor corresponding to apoprotein CII in this species. In the present study, we determined more accurately some characteristics of the enzyme activity inhibited by 0.3 M NaCl. Trout serum and high density lipoproteins (HDL) activated both rat and trout adipose tissue LPLs. A fraction of apo HDL obtained by gel filtration also activated the enzyme. The mean Mr was 10,000. Isoelectric focusing of the same fraction gave several bands of proteins with apparent pI in the range of 4.2-4.9. These results show that in trout, LPL is activated by a cofactor similar to that in mammals, the apo CII. In addition, a fraction mainly containing apo AI (+ traces of apo C) activated trout LPL and reinforced the activation by apo CII. These findings suggest that trout apo AI may promote the activating effect of apo CII on trout LPL.
D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D001059:Apoproteins / Q000378:metabolism*; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism; D012487:Salmonidae / Q000378:metabolism*; D014337:Trout / Q000378:metabolism*
D001059:Apoproteins; D008075:Lipoproteins, HDL; D008071:Lipoprotein Lipase