Endocrinology, Vol 100, 994-1001, Copyright © 1977 by Endocrine Society

ARTICLES

Presence of two neurophysins in the human pineal gland

AC Reinharz and MB Vallotton

The tentative identification of two neurophysins in human pineal glands is reported. The presence of these carrier-proteins for neurohormones was demonstrated by two different radioimmunossays: one highly specific for human pituitary estrogen-stimulated neurophysin (h-ESN) and the second for pituitary bovine neurophysin II (b-NII). These neurophysins accounted for about 0.425% of the total soluble pineal proteins. They were eluted from Sephadex G-75 column with the same elution volume as 125I labeled h-ESN. Their dilution curves were parallel to the standard curves of h-ESN and b-NII, respectively. Electrophoresis on polyacrylamide gel separated two distinct neurophysins. The less anodic neurophysin corresponding to b-NII and the faster moving one to h-ESN. The two proteins were named human pineal neurophysins I and II (h-PNI and h-PNII) in the order of their electrophoretic mobility. Purification of pineal neurophysins by isoelectric focusing resulted also in the separation of two neurophysins: one, recognized by antibody against h-ESN with an isoelectric point (pI) of 4.6, the other recognized by antibody against b-NII with a pI of 4.9. The presence of neurohormone(s), assessed by radioimmunoassay for [8-arginine] vasopressin, was also demonstrated. Under optimal conditions for the association the neurophysin and the neurohormone were eluted from Sephadex columns as a complex. This complex could be dissociated in 0.1N formic acid and the neurophysin and the neurohormone separated on Sephadex G-75.