ADP-ribosylation of p33 (mim-1 protein) and its effect on differentiation and growth of blood cells

精氨酸特异性adp核糖基转移酶催化adp核糖片段从NAD转移到靶蛋白的精氨酸残基。我们在鸡骨髓细胞和多形核细胞中观察了转移酶及其靶蛋白p33。对p33的氨基酸序列分析表明，该蛋白与myb诱导的髓样蛋白-1 （mim-1）的序列区域完全相同。6周龄鸡骨髓细胞中p33的含量明显高于外周血多形核细胞。骨髓细胞在含8%胎牛血清和2%热灭活鸡血清的培养液中以37℃的CO_2培养。在含有早幼粒细胞和多形核细胞的非贴壁细胞中检测到P33和转移酶，而在不含这些细胞的贴壁细胞中检测不到P33和转移酶。这些结果提示p33和转移酶可能参与骨髓细胞向粒细胞的分化。研究了从鸡外周多形核细胞中纯化的转移酶的自adp核糖基化。adp -核糖转移酶连锁在0.5 M羟氧胺中不稳定。在催化碱性受体（如聚l -精氨酸和p33）的adp核糖基化方面，自adp核糖基化转移酶的活性高于未修饰的转移酶，而在催化酸性蛋白（如酪蛋白）的adp核糖基化方面，修饰的转移酶的活性较低。因此，转移酶的自修饰明显地改变了其自身底物的特异性。

Arginine-specific ADP-ribosyltransferase catalyzes transfer of the ADP-ribose moiety from NAD to arginine residue(s) of target proteins. We observed the transferase and its target protein p33 in chicken bone-marrow cells and polymorphonuclear cells. Analysis of the amino acid sequence of p33 revealed that the protein was completely identical with the regions of the sequence deduced from mim-1 (myb-induced myeloid protein-1). The levels of p33 in bone-marrow celle from 6-week-old chiken were much higher than those of peripheral polymorphonuclear cells from the same chiken. The bone-marrow cells were cultured in CO_2 at 37ﾟC in growth medium containing 8% fetal calf serum and 2% heat-inactivated chiken serum. p33 and the transferase were detected in non-adherent cell fraction containing promyelocytes and polymorphonuclear cells but not in adherent cell fraction not containing those cells. These results indicate that p33 and the transferase may participate in the differentiation of bone-marrow cells to granulocytes. Auto-ADP-ribosylation of the transferase purified from chiken peripheral polymorphonuclear cells was investigated. The ADP-ribose-transferase linkage was labile in 0.5 M hydoroxylamine. The auto-ADP-ribosylated transferase showed higher activity than did the unmodified transferase in catalyzing ADP-ribosylation of the basic acceptor such as poly (L-arginine) and p33 while to ADP-ribosylate the acidic proteins such as casein, the modified transferase was less active. Thus, auto-modification of the transferase apparently alters the specificity of its own substrate.