Partial processing of the neuropeptide Y precursor in transfected CHO cells

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Abstract
The activation of regulatory peptides by post‐translational modification of their biosynthetic precursors is generally thought to occur only in neuroendocrine cells. We have selected clones of Chinese hamster ovary cells, a non‐neuroendocrine cell line, which were transfected with a eukaryotic expression vector coding for the precursor for neuropeptide Y. Although the majority of the immunoreactive NPY was found in the form of pro‐NPY, some degree of intracellular proteolytic processing of the precursor occurred in all clones. Part of the intracellular NPYimmunoreactivity was even correctly amidated. Extracellular degradation of pro‐NPY in the tissue culture medium generated immunoreactivity which corresponded in size to NPY. It is concluded that precursor processing can occur in non‐neuroendocrine cells both as a biological process within the cells and as apparent processing, degradation in the tissue culture medium.