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Oncogene. 1993 Feb;8(2):515-8.

Low molecular weight GTP-binding proteins are altered in platelet hyperaggregation in IDDM.

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Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-1060.


We examined the hypothesis that hyperaggregating platelets from patients with insulin dependent diabetes mellitus (IDDM) have an alteration in location and function of the guanine nucleotide (GTP)-binding proteins. Platelets from 10 IDDM and 12 age-matched healthy control subjects were collected and washed. Thrombin-induced platelet aggregation (0.025 and 0.05 units for 60 seconds) was increased in IDDM (8.3 +/- 1.8% vs 22.3 +/- 4.4%, P < .05 and 49.9 +/- 7.3% vs 70.9 +/- 7.0%, P < .05). Four small molecular weight GTP-binding proteins were identified by binding of [32P]-GTP on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the cytosol and membranes of these platelets. Each showed specificity for binding [32P]-GTP by competitive inhibition with unlabeled GTP. The total of the 27/28 kDa proteins was decreased in the membrane fraction (414 +/- 30 vs 252 +/- 40 dpm micrograms-1 protein x min, P < .05) and increased in the cytosolic fraction (62 +/- 8 vs 129 +/- 21 dpm unit-1 LDH x min, P < .05) in IDDM. The 21 kDa protein (60.3 +/- 3.5 vs 45.4 +/- 2.9 dpm micrograms-1 protein x min, P < .05) was decreased in platelet membrane in persons with IDDM. In conclusion, increased platelet aggregation in IDDM is accompanied by an altered cellular distribution of a 27/28 kDa GTP-binding protein. These data suggest that the low molecular weight GTP-binding proteins of the 27/28 kDa range may play an important regulatory role in the hyperaggregatory platelets in diabetes.

[Indexed for MEDLINE]

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