Glycosylation influences intracellular transit time and secretion rate of human prorenin in transfected cells.

The mouse pituitary tumour (AtT-20) cell transfected with the human renin gene has been shown to be a useful model system to study human renin biosynthesis. To investigate the influence of glycosylation on secretion of human renin from these cells, we performed pulse labelling experiments on transfected cells in the presence or absence of tunicamycin, a potent inhibitor of n-linked glycosylation. Intracellular and secreted renins were characterized by immunoprecipitation, sodium dodecyl sulphate (SDS) gel electrophoresis and fluorography. Our data showed that blockade of n-linked glycosylation reduced the intracellular transit time and increased the rate of prorenin secretion from transfected cells. We conclude that the carbohydrate moiety influences the kinetics of human renin secretion. This result provides one possible explanation for the observation that the secretion of glycosylated human renin is considerably slower than that of the unglycosylated mouse renin-2.