E. Rinderknecht is the first-listed author of primary studies with R. E. Humbel that chemically characterized serum polypeptides with insulin-like and growth-promoting activity. Their 1976 amino-terminal sequencing paper compared two preparations then called NSILA I and II and proposed the designation insulin-like growth factor from their biological properties and resemblance to insulin.[ref]
Of the first thirty-one residue positions examined, twenty-two were identical between the two polypeptides. That is about identity over the measured segment: substantial similarity, but not identity of the entire molecules. The measured segment and the comparison being made must therefore accompany any percentage. The later complete sequence of insulin-like growth factor 1 supplied a more extensive chemical description.[ref]
The scientific contribution is a shift from classifying preparations by their effects to distinguishing specific related proteins. Shared biological activity, shared amino-terminal residues and a complete molecular sequence are progressively different kinds of evidence; none should be silently substituted for another.
New to topics? Read the docs here!