Specific binding of the C-peptide of proinsulin was evaluated using a transplantable NEDH rat islet cell tumour predominantly composed of insulin-secreting B-cells. Cultured tumour B-cells exhibited greater than 90% viability assessed by trypan blue exclusion, and retained the ability to form tumours with accompanying hypoglycaemia and hyperinsulinaemia after reimplantation. During binding experiments with synthetic rat C-peptide I and iodinated tyrosylated rat C-peptide I, turnout B-cells exhibited 54±6% specific binding. Displacement of tracer increased with increasing concentrations of unlabelled rat C-peptide I (0.25–1,000 ng/ml), and the specificity of binding was substantiated by reduced displacement with human C-peptide. Scatchard analysis of specific C-peptide binding revealed a curvilinear plot with upward concavity. The demonstration of specific C-peptide binding to insulin-secreting B-cells provides evidence for a physiological role of proinsulin C-peptide.
Specific binding of the C-peptide of proinsulin to cultured B-cells from a transplantable rat islet cell tumor
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Peter R. Flatt, Sara K. Swanston-Flatt, Shelagh M. Hampton, Clifford J. Bailey, Vincent Marks; Specific binding of the C-peptide of proinsulin to cultured B-cells from a transplantable rat islet cell tumor. Biosci Rep 1 February 1986; 6 (2): 193–199. doi: https://doi.org/10.1007/BF01115006
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