Figure 3.
Insulin receptor substrate-1 (IRS1) protein levels and activity in skeletal muscle. (A) Immunoblot of IRS1 protein levels in total cell lysates from skeletal muscle biopsies. Levels of IRS1 were unchanged in patients with non-insulin-dependent diabetes mellitus when compared with controls. (B) Representative immunoblot of phosphotyrosine- IRS1 levels in skeletal muscle extracts as determined by phosphotyrosine immunoprecipitation and insulin receptor substrate-1 immunoblotting. (C) Quantification of total IRS1 levels in skeletal muscle biopsies in patient groups in optical units. (D) Quantification of phosphotyrosine- IRS1 levels in skeletal muscle biopsies in patient groups in optical units. **P = 0.001 vs. control.