Brown W E, Nobile V, Subramanian V, Shapiro R
Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
Genomics. 1995 Sep 1;29(1):200-6. doi: 10.1006/geno.1995.1232.
Angiogenin, a homologue of pancreatic ribonuclease, is a potent inducer of blood vessel formation. As an initial step toward investigating the in vivo functional role of this protein via gene disruption, we undertook the isolation of the angiogenin gene (Ang) from the 129 strain mouse, which will be used for generating targeting constructs. Unexpectedly, screening of a genomic library with an Ang gene probe obtained previously from the BALB/c strain yielded two new genes closely similar to Ang rather than Ang itself. One of these encodes a protein with 78% sequence identity to angiogenin and is designated "Angrp" for "angiogenin-related protein." The ribonucleolytic active site of angiogenin, which is critical for angiogenic activity, is completely conserved in Angrp, whereas a second essential site, thought to bind cellular receptors, is considerably different. Thus, the Angrp product may have a function distinct from that of angiogenin. The second gene obtained by library screening is a pseudogene, designated "Ang-ps1," that contains a frameshift mutation in the early part of the coding region. Although the Ang gene was not isolated from this library, it was possible to amplify this gene from 129 mouse genomic DNA by the polymerase chain reaction (PCR). Sequence analysis showed that the 129 strain Ang gene is identical to the BALB/c gene throughout the coding region. PCR cloning also yielded a second Ang-like pseudogene, designated "Ang-ps2." Southern blotting of genomic DNA confirmed the presence of Ang, Angrp, and at least one of the pseudogenes in an individual mouse and suggested that the mouse Ang gene family may contain more than the four members identified here.
血管生成素是胰腺核糖核酸酶的同源物，是一种强效的血管形成诱导剂。作为通过基因敲除研究该蛋白体内功能作用的第一步，我们着手从129品系小鼠中分离血管生成素基因（Ang），该基因将用于构建靶向载体。出乎意料的是，用先前从BALB/c品系获得的Ang基因探针筛选基因组文库时，得到的是两个与Ang非常相似的新基因，而非Ang本身。其中一个基因编码的蛋白与血管生成素的序列一致性为78%，被命名为“Angrp”，即“血管生成素相关蛋白”。血管生成素的核糖核酸酶活性位点对血管生成活性至关重要，在Angrp中完全保守，而另一个被认为与细胞受体结合的重要位点则有很大差异。因此，Angrp产物的功能可能与血管生成素不同。通过文库筛选获得的第二个基因是一个假基因，命名为“Ang-ps1”，其编码区前部存在移码突变。虽然未从该文库中分离出Ang基因，但通过聚合酶链反应（PCR）从129小鼠基因组DNA中扩增出了该基因。序列分析表明，129品系的Ang基因在整个编码区与BALB/c基因相同。PCR克隆还产生了第二个类似Ang的假基因，命名为“Ang-ps2”。基因组DNA的Southern印迹分析证实了单个小鼠中存在Ang、Angrp和至少一个假基因，并表明小鼠Ang基因家族可能包含多于此处鉴定的四个成员。
