Naim H Y, Sterchi E E, Lentze M J
Biochem J. 1987 Jan 15;241(2):427-34. doi: 10.1042/bj2410427.
The biosynthesis and maturation of the human intestinal lactase-phlorizin hydrolase (LPH; EC 3.2.1.23-3.2.1.62) has been studied in cultured intestinal biopsies and mucosal explants. Short time pulse labelling revealed on high mannose intermediate of Mr 215,000 which was converted upon endo-beta-N-acetylglucosaminidase H (endo-H) digestion to a polypeptide of Mr 200,000. The brush border form of LPH was revealed after longer pulse periods and has Mr 160,000. It possesses mainly complex oligosaccharide chains and, owing to its partial endo-H sensitivity, at least one chain of the high mannose type. Leupeptin partially inhibited the appearance of the Mr-160,000 polypeptide. Monensin treatment of biopsies resulted in the modification of the Mr-160,000 species to the Mr-140,000 molecule, which was endo-H sensitive. Pulse-chase analysis indicated a slow post-translational processing of the high mannose precursor (Mr 215,000) to yield the mature brush-border form (Mr 160,000) of LPH. Our results further indicate that LPH is synthesized as a single polypeptide precursor which is intracellularly cleaved to yield the mature brush border of LPH. The data presented suggest that this cleavage occurs during the translocation of the molecule across the Golgi complex.
已在培养的肠道活检组织和黏膜外植体中研究了人肠道乳糖酶 - 根皮苷水解酶（LPH；EC 3.2.1.23 - 3.2.1.62）的生物合成和成熟过程。短时间脉冲标记显示存在一个分子量为215,000的高甘露糖中间体，经内切β - N - 乙酰葡糖胺酶H（endo - H）消化后转化为分子量为200,000的多肽。较长脉冲期后显示出LPH的刷状缘形式，其分子量为160,000。它主要具有复杂的寡糖链，并且由于其对endo - H的部分敏感性，至少有一条高甘露糖型链。亮肽素部分抑制了分子量为160,000多肽的出现。对活检组织进行莫能菌素处理导致分子量为160,000的分子转变为分子量为140,000的分子，该分子对endo - H敏感。脉冲追踪分析表明，高甘露糖前体（分子量为215,000）向LPH成熟刷状缘形式（分子量为160,000）的翻译后加工过程缓慢。我们的结果进一步表明，LPH作为单一多肽前体合成，在细胞内被切割以产生LPH的成熟刷状缘。所呈现的数据表明这种切割发生在分子穿过高尔基体复合体的转运过程中。
