Rajarao S J, Canfield V A, Mohideen M A, Yan Y L, Postlethwait J H, Cheng K C, Levenson R
Department of Pharmacology, Pennsylvania State College of Medicine, Hershey, Pennsylvania 17033, USA.
Genome Res. 2001 Jul;11(7):1211-20. doi: 10.1101/gr.186001.
We have identified a cohort of zebrafish expressed sequence tags encoding eight Na,K-ATPase alpha subunits and five beta subunits. Sequence comparisons and phylogenetic analysis indicate that five of the zebrafish alpha subunit genes comprise an alpha1-like gene subfamily and two are orthologs of the mammalian alpha3 subunit gene. The remaining alpha subunit clone is most similar to the mammalian alpha2 subunit. Among the five beta subunit genes, two are orthologs of the mammalian beta1 isoform, one represents a beta2 ortholog, and two are orthologous to the mammalian beta3 subunit. Using zebrafish radiation hybrid and meiotic mapping panels, we determined linkage assignments for each alpha and beta subunit gene. Na,K-ATPase genes are dispersed in the zebrafish genome with the exception of four of the alpha1-like genes, which are tightly clustered on linkage group 1. Comparative mapping studies indicate that most of the zebrafish Na,K-ATPase genes localize to regions of conserved synteny between zebrafish and humans. The expression patterns of Na,K-ATPase alpha and beta subunit genes in zebrafish are quite distinctive. No two alpha or beta subunit genes exhibit the same expression profile. Together, our data imply a very high degree of Na,K-ATPase isoenzyme heterogeneity in zebrafish, with the potential for 40 structurally distinct alpha/beta subunit combinations. Differences in expression patterns of alpha and beta subunits suggest that many of the isoenzymes are also likely to exhibit differences in functional properties within specific cell and tissue types. Our studies form a framework for analyzing structure function relationships for sodium pump isoforms using reverse genetic approaches.
我们已鉴定出一群斑马鱼表达序列标签，它们编码八个钠钾ATP酶α亚基和五个β亚基。序列比较和系统发育分析表明，五个斑马鱼α亚基基因构成一个α1样基因亚家族，两个是哺乳动物α3亚基基因的直系同源物。其余的α亚基克隆与哺乳动物α2亚基最为相似。在五个β亚基基因中，两个是哺乳动物β1同工型的直系同源物，一个代表β2直系同源物，两个与哺乳动物β3亚基直系同源。利用斑马鱼辐射杂种图谱和减数分裂图谱面板，我们确定了每个α和β亚基基因的连锁定位。除了四个α1样基因紧密聚集在连锁群1上外，钠钾ATP酶基因分散在斑马鱼基因组中。比较图谱研究表明，大多数斑马鱼钠钾ATP酶基因定位于斑马鱼和人类之间保守同线性的区域。斑马鱼中钠钾ATP酶α和β亚基基因的表达模式非常独特。没有两个α或β亚基基因表现出相同的表达谱。总之，我们的数据表明斑马鱼中钠钾ATP酶同工酶具有高度异质性，可能存在40种结构不同的α/β亚基组合。α和β亚基表达模式的差异表明，许多同工酶在特定细胞和组织类型中也可能表现出功能特性的差异。我们的研究为使用反向遗传学方法分析钠泵同工型的结构功能关系建立了一个框架。
