{'fraction_non_alphanumeric': 0.03436426116838488, 'fraction_numerical': 0.001718213058419244, 'mean_word_length': 5.072916666666667, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Pre-prolactin accumulates in rat pituitary cells incubated with a threonine analog.

The proteolytic processing of rat pre-prolactin (Pre-Prl) to prolactin in isolated hemipituitaries was inhibited by the threonine analog, beta-hydroxynorvaline (Hnv). Pre-Prl accumulated as a major labeled intracellular product, even during pulse labeling longer than 2 h, but it was not secreted. Inhibition of Pre-Prl processing may result from incorporation of Hnv at the Pre-Prl cleavage site. This system offers the opportunity to study the disposition of an accumulated pre-protein in cells.