Insulin receptors on Chinese hamster ovary (CHO) cells: altered insulin binding to glycosylation mutants

We have identified and characterized insulin receptors on Chinese hamster ovary (CHO) cells. Insulin binds in a time, temperature and pH dependent fashion and insulin analogues compete for 125I-insulin binding in order of their biological potencies. Furthermore, two CHO cell glycosylation mutants, B4-2-1, lacking high mannose containing glycoproteins, and Lec 1.3c, lacking complex carbohydrate containing glycoproteins, bind insulin with a much higher and lower affinity respectively than wild type cells. This is the first report of insulin receptors on CHO cells and the first to use glycosylation mutants to study the effects of abnormal carbohydrates on insulin binding.