Lussier M, Camirand A, Sdicu A M, Bussey H
Department of Biology, McGill University, Montréal, Québec, Canada.
Yeast. 1993 Oct;9(10):1057-63. doi: 10.1002/yea.320091004.
The KTR2 gene from Saccharomyces cerevisiae was identified by polymerase chain reaction amplification of genomic DNA using primers derived from regions of high homology between the products of three yeast genes, KRE2, YUR1 and KTR1. The product encoded by the KTR2 gene is a predicted type II membrane protein of 425 amino acid residues with a short cytoplasmic N-terminus, a membrane-spanning region and a large lumenal domain containing residues with a short cytoplasmic N-terminus, a membrane-spanning region and a large lumenal domain containing four potential N-glycosylation sites. Ktr2p has 58% identity with Yur1p, 39% with Ktr1p and 34% with Kre2p. One member of this gene family, KRE2 (also known as MNT1; Häusler and Robbins, 1992), encodes an alpha-1,2 mannosyltransferase which adds the third mannose onto O-linked glycoprotein side-chains (Häusler et al., 1992). In contrast to KRE2 null mutants, which produce shortened (two-mannose) chains, mutants harboring a KTR2 gene disruption synthesize O-linked chains with the wild-type patterns of five mannose residues. A null mutation in KTR2 leads to partial resistance to killer toxin and hints that KTR2, which encodes a putative mannosyltransferase, is involved in extracellular matrix assembly.
利用从酵母三个基因KRE2、YUR1和KTR1的产物之间高度同源区域衍生而来的引物，通过聚合酶链反应扩增酿酒酵母的基因组DNA，从而鉴定出了KTR2基因。KTR2基因编码的产物是一种预测的II型膜蛋白，含有425个氨基酸残基，其N端细胞质区域较短，有一个跨膜区域和一个大的腔结构域，该腔结构域含有四个潜在的N-糖基化位点，其N端细胞质区域较短，有一个跨膜区域和一个大的腔结构域。Ktr2p与Yur1p的同源性为58%，与Ktr1p的同源性为39%，与Kre2p的同源性为34%。该基因家族的一个成员KRE2（也称为MNT1；Häusler和Robbins，1992）编码一种α-1,2-甘露糖基转移酶，该酶将第三个甘露糖添加到O-连接糖蛋白侧链上（Häusler等人，1992）。与产生缩短（两个甘露糖）链的KRE2缺失突变体不同，携带KTR2基因破坏的突变体合成的O-连接链具有五个甘露糖残基的野生型模式。KTR2中的无效突变导致对杀伤毒素产生部分抗性，并暗示编码假定甘露糖基转移酶的KTR2参与细胞外基质组装。
