Electrophoretic andImmunological Characterization ofRatNeurophysin

Thepeptide hormonesoxytocin andvasopressin canbeextracted fromthemammalianposterior pituitary glandasa complexwiththeprotein neurophysin (Acher, Manoussos & Olivry, 1955). Thesuggestion bySawyer(1961) thatneurophysin isa 'carrier' forthehormoneswithinthehypothalamo-neurohypophysial systemwassupported bythefinding thatinhomogenates ofoxpituitary glands, neurophysin andthehormones werelocated together ina sedimentable fraction (Ginsburg & Ireland, 1966).A highly purified preparation of neurosecretory vesicles (Dean& Hope,1967)was foundtocontain twoprincipal binding proteins, whichwereisolated andnamedneurophysin-I and -II(Hollenberg H Dean&Hope,1968). Theneurosecretory vesicles havebeenpartially separated insucrose density gradients into afraction oflowerdensity containing neurophysin-I andoxytocin, andafraction ofhigher density containing neurophysin-II and[8-arginine]-vasopressin