| First Author | Voliovitch H | Year | 1995 |
| Journal | J Biol Chem | Volume | 270 |
| Issue | 30 | Pages | 18083-7 |
| PubMed ID | 7629118 | Mgi Jnum | J:27456 |
| Mgi Id | MGI:74937 | Doi | 10.1074/jbc.270.30.18083 |
| Citation | Voliovitch H, et al. (1995) Tyrosine phosphorylation of insulin receptor substrate-1 in vivo depends upon the presence of its pleckstrin homology region. J Biol Chem 270(30):18083-7 |
| abstractText | To characterize the structural basis for the interactions between the insulin receptor (IR) and its major substrate, insulin receptor substrate-1 (IRS-1), a segment of the NH2-terminal region of IRS-1 (Pro5-Pro65) was deleted. This region contains the first four conserved boxes of a pleckstrin homology (PH) domain, located at the NH2-terminal part of IRS-1. COS-7 cells were then cotransfected with the genes coding for IR and a wild-type (WT) or a mutated form of IRS-1. IRS-1 delta PH underwent significantly reduced insulin-dependent tyrosine phosphorylation compared with WT IRS-1. The reduced in vivo tyrosine phosphorylation of IRS-1 delta PH was accompanied by reduced association between IRS-1 delta PH and its downstream effector p85 regulatory subunit of phosphatidylinositol-3 kinase. In contrast, both WT IRS-1 and IRS-1 delta PH underwent comparable insulin-dependent tyrosine phosphorylation in vitro when incubated with partially purified insulin receptor kinase. These findings suggest that the overall structure of IRS-1 is not altered by deletion of its PH domain and that the PH domain is not the main site for protein-protein interactions between the insulin receptor and IRS-1, at least in vitro. In conclusion, the PH region might facilitate in vivo binding of IRS-1 to membrane phospholipids or other cellular constituents in close proximity to the IR, whereas the actual interactions with the IR are presumably mediated through other domains of the IRS-1 molecule. This could account for the fact that partial deletion of the PH domain selectively impairs the in vivo interactions between the insulin receptor and IRS-1, whereas their in vitro interactions remain unaffected. |
