Loftus S K, Shiang R, Warrington J A, Bengtsson U, McPherson J D, Wasmuth J J
Department of Biological Chemistry, College of Medicine, University of California, Irvine 92717.
Cytogenet Cell Genet. 1994;67(2):69-74. doi: 10.1159/000133802.
The distal portion of the long arm of chromosome 5 (5q) contains a large number of genes encoding membrane receptors belonging to various gene families, including G protein-coupled adrenergic receptors. Previous reports indicated that the genes for two of the adrenergic receptors, ADRB2 and ADRA1B, were within 300 kb of one another on 5q. In an effort to determine if a third adrenergic receptor assigned to 5q, ADRA1A, was physically close to the genes encoding the other adrenergic receptors, we attempted to place all three loci on a radiation hybrid map of 5q. The results conflicted with previous mapping results in two ways. First, ADRA1B is on 5q but is several million bases, rather than a few hundred thousand bases, from ADRB2. Second, ADRA1A is not on chromosome 5, but rather on chromosome 20. Thus, even though 5q contains an extraordinary number of genes encoding receptors for various hormones, growth factors, and neurotransmitters, there is no particular clustering of genes encoding adrenergic receptors in this region.
5号染色体长臂的远端部分（5q）包含大量编码属于各种基因家族的膜受体的基因，包括G蛋白偶联肾上腺素能受体。先前的报道表明，两种肾上腺素能受体ADRB2和ADRA1B的基因在5q上彼此相距300 kb以内。为了确定定位于5q的第三种肾上腺素能受体ADRA1A是否在物理位置上与编码其他肾上腺素能受体的基因接近，我们试图将所有三个基因座定位到5q的辐射杂种图谱上。结果在两个方面与先前的定位结果相冲突。首先，ADRA1B位于5q上，但与ADRB2相距数百万个碱基，而不是几十万碱基。其次，ADRA1A不在5号染色体上，而是在20号染色体上。因此，尽管5q包含数量异常多的编码各种激素、生长因子和神经递质受体的基因，但该区域中编码肾上腺素能受体的基因并没有特别的聚类现象。
