Degradation of relaxin family peptides by insulin-degrading enzyme.
Insulin-degrading enzyme (IDE) is a ubiquitously expressed metalloproteinase responsible for the intracellular degradation of insulin. IDE also interacts with other members of the insulin superfamily, including relaxin, but no studies have been reported regarding the interaction of other relaxin-like peptides with IDE. In this study, we determined that relaxin, relaxin-3, and InsL3 all competitively inhibited the degradation of insulin by IDE to different degrees, and all inhibited covalent cross-linking of insulin to IDE. Each of the peptides was degraded by IDE to various degrees (insulin > relaxin > InsL3 = relaxin-3). In summary, relaxin, InsL3, and relaxin-3 all bound to IDE, competed for the binding and degradation of insulin, and were all substrates for the proteolytic activity of IDE. Therefore, it is possible that in addition to insulin, IDE may be important for the cellular proteolysis of relaxin, InsL3, and relaxin-3.
VA Medical Center, Omaha, Nebraska 68105, USA. rgbennet@unmc.edu
Robert G
RG
Bennett
Dean G
DG
Heimann
Frederick G
FG
Hamel
D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007339:Insulysin / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D012065:Relaxin / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared
D007328:Insulin; C084797:Leydig insulin-like protein; D011506:Proteins; C480238:RLN3 protein, human; D012065:Relaxin; D007339:Insulysin