Dunlevy J R, Berryhill B L, Vergnes J P, SundarRaj N, Hassell J R
Shriners Hospitals for Children-Tampa, College of Medicine, University of South Florida, 12502 North Pine Drive, Tampa, Florida 33612, USA.
Genomics. 1999 Dec 15;62(3):519-24. doi: 10.1006/geno.1999.5994.
The cornea contains, as a major element, a transparent stroma produced and maintained by keratocytes (fibroblasts). Through molecular biology studies using cultured human corneal fibroblasts, a cDNA that was shown to be novel was isolated and sequenced. This novel gene product, named SH3-domain binding protein 4 (SH3BP4), contains a 5.6-kb message that is present in normal human corneal fibroblasts and all tissues examined, with higher levels in pancreas, placenta, heart, and kidney. SH3BP4 was localized by FISH analysis to human chromosome 2q37.1-q37.2 near the telomere. The deduced sequence for SH3BP4 was found to contain a 963-amino-acid open reading frame that has homology to a 479-amino-acid protein in GenBank called EH-binding protein. Although the entire sequence of EH-binding protein aligns with SH3BP4, the alignment is not complete or contiguous. Therefore, SH3BP4 has an additional 73 amino acids at the N-terminus and an additional 411 amino acids near the C-terminus that are not present in EH-binding protein. Consensus sequence domains identified in SH3BP4 include a SH3 domain, three N-P-F motifs, a P-X-X-P motif noted for binding to SH3 domains, a bipartite nuclear targeting signal, and a tyrosine phosphorylation site. SH3BP4 homologies and consensus sequence sites indicate that it may be involved in a newly identified cascade of proteins involved in endocytosis, intracellular sorting, and the cell cycle.
角膜的主要成分是由角膜细胞（成纤维细胞）产生并维持的透明基质。通过对培养的人角膜成纤维细胞进行分子生物学研究，分离并测序了一个显示为新的cDNA。这个新的基因产物，命名为SH3结构域结合蛋白4（SH3BP4），含有一个5.6 kb的信息，存在于正常人角膜成纤维细胞和所有检测的组织中，在胰腺、胎盘、心脏和肾脏中水平更高。通过荧光原位杂交分析，SH3BP4定位于人染色体2q37.1 - q37.2靠近端粒处。发现SH3BP4的推导序列包含一个963个氨基酸的开放阅读框，与GenBank中一个名为EH结合蛋白的479个氨基酸的蛋白质具有同源性。虽然EH结合蛋白的整个序列与SH3BP4对齐，但对齐并不完整或连续。因此，SH3BP4在N端有额外的73个氨基酸，在C端附近有额外的411个氨基酸，这些在EH结合蛋白中不存在。在SH3BP4中鉴定出的共有序列结构域包括一个SH3结构域、三个N - P - F基序、一个以与SH3结构域结合而闻名的P - X - X - P基序、一个双分型核定位信号和一个酪氨酸磷酸化位点。SH3BP4的同源性和共有序列位点表明它可能参与了新发现的一系列与内吞作用、细胞内分选和细胞周期有关的蛋白质。
