Glucagon and its Family Revisited

Considered for decades as a contaminant of insulin preparations, gluca-gon was among the very first hormones to be isolated, purified, sequenced, and synthesized during the late 1950s. The field of glucagon research exploded after R.H. Unger and his colleagues in Dallas, TX, described a method permitting its measurement in the plasma by radioimmunoassay. Such assay made it possible to firmly establish the basic principles of glucagon physiology and to discover its pathophysiology. More recently, important progress has been made in exploring the molecular biology of this hormone: the glucagon gene and the glu-cagon-receptor gene have been identified and their expression investigated. Furthermore, the processing of the glucagon gene product has been elucidated and the function of the members of the glucagon family has been clarified. Finally, current investigations are in progress to develop glucagon agonists and antagonists and to identify new modes of administration of the hormone. These various topics will be considered in this review.