| Abstract: | The pattern of cellular protein glycosylation can be altered in CHO cells by glucose starvation. When wild type CHO cells are deprived of glucose, 125I-insulin binding increases from a B/F of 0.033 +/- 0.004 to 0.063 +/- 0.011, due to an increase in receptor affinity. The already elevated insulin binding to mutant B4-2-1 CHO cells, whose genetic defect causes abnormal glycosylation mimicking the pattern seen in the glucose starved normal cells, is not affected by glucose starvation. In neither cell line is 125I-IGF-I binding affected by glucose starvation. These data support the hypothesis that abnormal glycosylation can alter insulin binding to its receptor. Furthermore, there is a striking difference in the susceptibility of IGF-I and insulin receptors to alterations in glycosylation. |
