Figure 1

Biosynthesis of POMC in hyperactive and basally active Xenopus melanotrope cells. A, Neurointermediate lobes (NILs) from black-adapted (BA) and white-adapted (WA) animals were pulse labelled with [³⁵S]methionine/cysteine for 30 minutes and subsequently chased for three hours. The WA NILs were pulsed and chased in the presence of 10^-6 M apomorphine to retain their basally active characteristics. Aliquots of the cell lysates (cells; BA: 5% of total lysate, WA: 10%) and the incubation media (media; BA: 10%, WA: 20%) were analysed by 15% SDS-PAGE and autoradiography. B, The amount of 37 K POMC remaining in the cells following the pulse-chase incubation. C, The total amounts (cells + media) of 18 K and 18 K* POMC produced during the pulse-chase incubations. The 18 K*/18 K ratios are given above the bars. Data are shown as means +/- s.e.m.; **, p < 0.01; all bars represent four animals.