Characterisation of an intermediate in neurophysin biosynthesis in the guinea pig

Abstract
In addition to oxytocin (OT), vasopressin (AVP) and their respective neurophysins (NPs), another [35S]cysteine incorporating component is present in the guinea pig neurohypophysis. Gel filtration and Con A affinity chromatography revealed that this component was larger than NP and was glycosylated. NP‐immunoreactivity was assessed using antisera which distinguish the OT‐ and AVP‐related NPs. Whilst the anti‐NP antiserum detected only one component (guinea pig NP), the anti‐NP antiserum detected both NP and the glycosylated 35S‐labelled component. These results suggest that a significant amount of NP in guinea pig neural lobes bears a glycopeptide extension and represents a partially processed form of the AVP precursor in this species.