Blanco-Arias Patricia, Sargent Carole A, Affara Nabeel A
Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
Mamm Genome. 2004 Jan;15(1):41-52. doi: 10.1007/s00335-003-3028-7.
The gene-poor, hominid-specific Yp11.2/Xq21.3 X-Y homology block encodes two members of the protocadherin group of cell surface molecules, PCDHX and PCDHY. These two genes, mainly expressed in brain, were known to be composed of at least six exons sharing 98.1% DNA identity. The genomic structure of PCDHX/ Y has been reanalyzed in detail, uncovering the existence of at least 11 more exons spanning more than 700 kb. Many of these exons located at the 5' and 3' ends of PCDHX/ Y undergo differential and alternative splicing. Seven of the exons have been found to use alternative splice sites. Most of these variants are expressed within the brain, although some isoforms exhibit a more ubiquitous distribution pattern. PCDHX/ Y transcription appears to be driven from two alternative promoters located usptream of exon 1 and exon 4.1. Assuming that the splicing events at the 5' and 3' ends of these genes are independent of one another, potentially up to 360 different mRNAs could be produced. The main impact on protein function is predicted to be in the efficiency of translation, post-translational processing within the cell, and structure of the cytoplasmic domain that may influence any role the genes have in signaling.
基因贫乏的、人类特有的Yp11.2/Xq21.3 X-Y同源区段编码细胞表面分子原钙黏蛋白家族的两个成员，即PCDHX和PCDHY。已知这两个主要在大脑中表达的基因由至少六个外显子组成，它们的DNA一致性为98.1%。已对PCDHX/Y的基因组结构进行了详细重新分析，发现至少还有11个外显子，跨越超过700 kb。这些外显子中许多位于PCDHX/Y的5'和3'端，会发生差异剪接和可变剪接。已发现其中七个外显子使用可变剪接位点。这些变体中的大多数在大脑中表达，不过一些异构体表现出更广泛的分布模式。PCDHX/Y的转录似乎由位于外显子1和外显子4.1上游的两个可变启动子驱动。假设这些基因5'和3'端的剪接事件相互独立，则可能产生多达360种不同的mRNA。预计对蛋白质功能的主要影响在于翻译效率、细胞内的翻译后加工以及可能影响这些基因在信号传导中所起任何作用的细胞质结构域的结构。
