Structural basis of the aberrant receptor binding properties of hagfish and lamprey insulins.

The insulin from the Atlantic hagfish (Myxine glutinosa) has been one of the most studied insulins from both a structural and a biological viewpoint; however, some aspects of its biology remain controversial, and there has been no satisfying structural explanation for its low biological potency. We have re-examined the receptor binding kinetics, as well as the metabolic and mitogenic properties, of this phylogenetically ancient insulin, as well as that from another extant representative of the ancient chordates, the river lamprey (Lampetra fluviatilis). Both insulins share unusual binding kinetics and biological properties with insulin analogues that have single mutations at residues that contribute to the hexamerization surface.

IRS-4 mediated mitogenic signalling by insulin and growth hormone in LB cells, a murine T-cell lymphoma devoid of IGF-I receptors.

Insulin and growth hormone (GH) induce mitogenic and metabolic signals in cells, GH either directly or indirectly via IGF-I production. We have studied a spontaneous murine T-cell lymphoma (LB cells) devoid of IGF-1 receptors in which proliferation is maintained by insulin [Int. J.