Figure 1.

Mouse platelets express functional IRs. (A) Immunoblotting demonstrated that IR, IGF1R, IRS-1, and IRS-2 are expressed in human and mouse platelets. IRS-3 was expressed only in mouse platelets (n = 5). (B) Time course of insulin (20 nM) stimulation of mouse platelets showing tyrosine phosphorylation of IR and the PI3K effector Akt (Ser⁴⁷³; n = 3). (C) Insulin (20 nM, 5 min) stimulation of mouse platelets leads to tyrosine phosphorylation of IRS-1 (i) and IRS-2 (ii) and induces their association with the PI3K regulatory subunit p85 (i–iii) (n = 3). Furthermore, tyrosine-phosphorylated (pY) proteins at 160, 100, and 60 kDa (see arrows) were found to be associated with p85 after insulin stimulation (iii). Phosphorylation of the indicated proteins was assessed by western blotting of either whole cell lysates or immunoprecipitates (IP). Membranes were reprobed to confirm equal loading.