Hennig D, Scales S J, Moreau A, Murley L L, De Mey J, Kreis T E
Department of Supramolecular and Cell Biology, Institut Jacques Monod, 2 Place Jussieu, 75251 Paris, France.
J Biol Chem. 1998 Jul 31;273(31):19602-11. doi: 10.1074/jbc.273.31.19602.
A protein of 60 kDa (p60) has been identified using a quantitative in vitro vesicle-microtubule binding assay. Purified p60 induces co-sedimentation with microtubules of trans-Golgi network-derived vesicles isolated from polarized, perforated Madin-Darby canine kidney cells. Sequencing of the cDNA coding for this protein revealed that it is the chicken homologue of formiminotransferase cyclodeaminase (FTCD), a liver-specific enzyme involved in the histidine degradation pathway. Purified p60 from chicken liver has formiminotransferase activity, confirming that it is FTCD or an isoform of this enzyme. Isoforms of FTCD were identified in chicken hepatoma and HeLa cells, and immunolocalize to the region of the Golgi complex and vesicular structures in its vicinity. Furthermore, 58K, a previously identified microtubule-binding Golgi protein from rat liver (Bloom, G. S., and Brashear, T. A. (1989) J. Biol. Chem. 264, 16083-16092), is identical to FTCD. Both proteins co-purify with microtubules and co-localize with membranes of the Golgi complex. The capacity of FTCD to bind both to microtubules and Golgi-derived membranes may suggest that this protein, or one of its isoforms, might have in addition to its enzymatic activity, a second physiological function in mediating interaction of Golgi-derived membranes with microtubules.
通过定量体外囊泡-微管结合试验鉴定出一种60 kDa的蛋白质（p60）。纯化的p60可诱导从极化的、穿孔的Madin-Darby犬肾细胞中分离出的反式高尔基体网络来源的囊泡与微管共沉降。编码该蛋白质的cDNA测序显示，它是亚胺甲基转移酶环化脱氨酶（FTCD）的鸡同源物，FTCD是一种参与组氨酸降解途径的肝脏特异性酶。从鸡肝中纯化的p60具有亚胺甲基转移酶活性，证实它是FTCD或该酶的一种同工型。在鸡肝癌细胞和HeLa细胞中鉴定出了FTCD的同工型，并且免疫定位到高尔基体复合体区域及其附近的囊泡结构。此外，58K是先前从大鼠肝脏中鉴定出的一种与微管结合的高尔基体蛋白（Bloom, G. S., and Brashear, T. A. (1989) J. Biol. Chem. 264, 16083 - 16092），它与FTCD相同。这两种蛋白质都与微管共纯化，并与高尔基体复合体的膜共定位。FTCD既能与微管结合又能与高尔基体来源的膜结合，这可能表明该蛋白质或其同工型之一，除了其酶活性外，在介导高尔基体来源的膜与微管的相互作用中可能还具有第二种生理功能。
