Okuda Tetsuya, Sawada Toshihiko, Nakano Hirofumi, Matsubara Kazumi, Matsuda Yoichi, Fukuta Masakazu, Habuchi Osami
Department of Life Science, Aichi University of Education, Igaya-cho, Kariya, Aichi 448-8542.
J Biochem. 2003 Jul;134(1):111-20. doi: 10.1093/jb/mvg118.
N-Acetylgalactosamine 4-sulfotransferase (GalNAc4ST) transfers sulfate to position 4 of nonreducing terminal GalNAc residues. We previously cloned human GalNAc4ST-1 cDNA. In this paper, we report the cloning, characterization and chromosomal mapping of mouse GalNAc4ST-1 and GalNAc4ST-2. Mouse GalNAc4ST-1 and GalNAc4ST-2 contain single open reading frames that predict type II transmembrane proteins composed of 417 and 413 amino acid residues, respectively. The amino acid sequence identity between the two isoforms is 49%. When the cDNA was transfected to COS-7 cells, sulfotransferase activities toward carbonic anhydrase VI and GalNAcbeta1-4GlcNAcbeta1-octyl were overexpressed, but the sulfotransferase activity toward chondroitin showed no increase over the control level. Northern blot analysis showed that the 2.4 kb messages of GalNAc4ST-1 and GalNAc4ST-2 were strongly expressed in the kidney, where both of the human isoforms were hardly expressed. Reverse transcription-PCR analysis showed that, unlike human GalNAc4ST-1, the expression of mouse GalNAc4ST-1 in the pituitary gland was only marginal, while that of GalNAc4ST-2 in the pituitary gland was as high as that in the kidney. These results suggest that the functions of the two GalNAc4ST isoforms may differ between human and mouse. By fluorescence in situ hybridization, the GalNAc4ST-1 and GalNAc4ST-2 genes were localized to mouse chromosome 7B3 distal-B5 proximal and chromosome 18A2 distal-B1 proximal, respectively.
N-乙酰半乳糖胺4-硫酸转移酶（GalNAc4ST）将硫酸基团转移至非还原末端GalNAc残基的4位。我们之前克隆了人GalNAc4ST-1 cDNA。在本文中，我们报告了小鼠GalNAc4ST-1和GalNAc4ST-2的克隆、特性鉴定及染色体定位。小鼠GalNAc4ST-1和GalNAc4ST-2含有单一开放阅读框，分别预测由417和413个氨基酸残基组成的II型跨膜蛋白。这两种同工型之间的氨基酸序列同一性为49%。当将该cDNA转染至COS-7细胞时，对碳酸酐酶VI和GalNAcbeta1-4GlcNAcbeta1-辛酯的硫酸转移酶活性被过度表达，但对软骨素的硫酸转移酶活性未显示出比对照水平有增加。Northern印迹分析表明，GalNAc4ST-1和GalNAc4ST-2的2.4 kb信使RNA在肾脏中强烈表达，而两种人同工型在肾脏中几乎不表达。逆转录-PCR分析表明，与人类GalNAc4ST-1不同，小鼠GalNAc4ST-1在垂体中的表达仅为微量，而GalNAc4ST-2在垂体中的表达与在肾脏中的表达一样高。这些结果表明，两种GalNAc4ST同工型的功能在人和小鼠之间可能存在差异。通过荧光原位杂交，GalNAc4ST-1和GalNAc4ST-2基因分别定位于小鼠染色体7B3远端 - B5近端和染色体18A2远端 - B1近端。
