Inhibition of insulin degradation by insulin-like growth factors.
The effect of insulin-like growth factors (IGF 1 and IGF 2) on insulin degradation was studied with the use of a preparation of insulin protease from rat skeletal muscle. Insulin, IGF 1 and IGF 2 inhibited 125I-insulin degradation by this enzyme. IGF 2 was the most potent inhibitor and IGF 1 was the least potent. These results are similar to what has been reported previously for the insulin-degrading activity in the serum of a diabetic patient who was resistant to sc and im insulin. Insulin protease also degraded 125I-iodo IGF 1 and 125I-iodo IGF 2. 125I-iodo IGF 2 was degraded more rapidly than was 125I-iodo IGF 1. 125I-iodoinsulin was degraded more rapidly than 125I-iodo IGF 2. With all three peptides, immunoprecipitation was a more sensitive measure of degradation than was trichloroacetic acid precipitation. The results suggest that insulin protease may be responsible for the degradation of insulin-like growth factors as well as of insulin.
D000818:Animals; D007163:Immunosorbent Techniques; D007328:Insulin / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology*; D007339:Insulysin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009132:Muscles / Q000201:enzymology*; D010455:Peptides / Q000494:pharmacology*; D011480:Protease Inhibitors; D051381:Rats; D013002:Somatomedins / Q000494:pharmacology*
D007328:Insulin; D010455:Peptides; D011480:Protease Inhibitors; D013002:Somatomedins; C008147:insulin, iodo-; D007339:Insulysin