The neurophysins are a family of cystine-rich proteins found associated with the hormones oxytocin and vasopressin in the neurosecretory granules of the posterior pituitary. Until now, neurophysins have been investigated mainly in the ox and the pig (Rauch, Hollenberg & Hope, 1969; Uttenthal & Hope, 1970), but for experimental purposes knowledge of the properties of the neurophysins of laboratory animals is desirable. On the basis of [35S]cysteine incorporation studies in vivo, two of the main components seen after polyacrylamide-gel electrophoresis of rat neurohypophysial extracts have been tentatively identified as neurophysins (Pickering, Jones & Burford, 1971; Burford & Pickering, 1971). In a parallel study, Norström, Sjöstrand, Livett, Uttenthal & Hope (1971) found a single protein band, in the same region on polyacrylamide gels, which cross-reacted with antibodies to porcine neurophysin. The present communication describes the initial chemical characterization of rat neurohypophysial proteins.
Acetone-dried posterior pituitary powder (136 mg) obtained from