Fischer H D, Natowicz M, Sly W S, Bretthauer R K
J Cell Biol. 1980 Jan;84(1):77-86. doi: 10.1083/jcb.84.1.77.
Mild acid hydrolysis of phosphomannan secreted by the yeast hansenula holstii (NRRL Y- 2448) produces two phosphomannyl fragments which differ strikingly in their potency as inhibitors of pinocytosis of human beta-glucuronidase by human fibroblasts. The larger molecular weight polyphosphomonoester fragment is 100,000-fold more potent an inhibitor of enzyme uptake than the smaller penta-mannosyl-monophosphate fragment. Binding to attached fibroblasts at 3 degrees C was much greater with the polyphosphomonoester fragment than with the pentamannosyl-monophosphate. The larger molecular weight fragment was also subject to adsorptive pinocytosis and was taken up by fibroblasts at a rate 30- fold greater than the rate of uptake of pentamannosyl-monophosphate. Evidence that the polyphosphomonoester fragment is taken up by the phosphomannosyl-recognition system that mediates uptake of lysosomal enzymes includes: (a) its pinocytosis is inhibited by the same compounds that competitively inhibit enzyme pinocytosis (mannose-6-phosphate and phosphomannan from saccharomyces cerevisiae mutant mnn-1); (b) alkaline phosphatase treatment greatly reduces its susceptibility to pinocytosis; (c) its pinocytosis is competitively inhibited by high-uptake human beta-glucuronidase; and (d) this inhibition by high-uptake enzyme is dramatically reduced by prior treatment of the enzyme with alkaline phosphatase or endoglycosidase-H. Endoglycosidase-H treatment human beta-glucuronidase dramatically reduced its susceptibility to pinocytosis by fibroblasts. The phosphomannosyl components of high- uptake enzyme released by endoglycosidase-H treatment were much less effective inhibitors of polyphosphomonoester pinocytosis than when present on the phosphomannyl-enzyme. These results suggest that high-uptake acid hydrolases may be polyvalent ligands analogous to the polyphosphomonoester mannan fragment whose pinocytosis depends on interaction of more than one phospho-mannosyl recognition marker with pinocytosis receptors on fibroblasts.
对霍氏汉逊酵母（NRRL Y - 2448）分泌的磷酸甘露聚糖进行温和酸水解，可产生两个磷酸甘露糖片段，它们作为人成纤维细胞对人β - 葡萄糖醛酸酶胞饮作用抑制剂的效力差异显著。分子量较大的多磷酸单酯片段作为酶摄取抑制剂的效力比分子量较小的五甘露糖基单磷酸片段高100000倍。在3℃下，多磷酸单酯片段与贴壁成纤维细胞的结合比五甘露糖基单磷酸片段强得多。分子量较大的片段也会发生吸附性胞饮作用，其被成纤维细胞摄取的速率比五甘露糖基单磷酸的摄取速率高30倍。多磷酸单酯片段通过介导溶酶体酶摄取的磷酸甘露糖识别系统被摄取的证据包括：（a）其胞饮作用受到竞争性抑制酶胞饮作用的相同化合物（甘露糖 - 6 - 磷酸和来自酿酒酵母突变体mnn - 1的磷酸甘露聚糖）的抑制；（b）碱性磷酸酶处理大大降低了其对胞饮作用的敏感性；（c）其胞饮作用受到高摄取量的人β - 葡萄糖醛酸酶的竞争性抑制；（d）高摄取量的酶的这种抑制作用在该酶先用碱性磷酸酶或内切糖苷酶 - H处理后会显著降低。内切糖苷酶 - H处理人β - 葡萄糖醛酸酶会显著降低其对成纤维细胞胞饮作用的敏感性。内切糖苷酶 - H处理释放的高摄取量酶的磷酸甘露糖成分作为多磷酸单酯胞饮作用抑制剂的效果比存在于磷酸甘露糖基酶上时要差得多。这些结果表明，高摄取量的酸性水解酶可能是多价配体，类似于多磷酸单酯甘露聚糖片段，其胞饮作用取决于不止一个磷酸甘露糖识别标记与成纤维细胞上的胞饮作用受体的相互作用。
