Snyder M, Davidson N
J Mol Biol. 1983 May 15;166(2):101-18. doi: 10.1016/s0022-2836(83)80001-1.
Three Drosophila genes that are clustered within 8 X 10(3) bases of DNA at the chromosomal region 44D have been identified and mapped, and the gene cluster entirely sequenced. The three genes are 55 to 60% homologous in DNA sequence. One gene contains an intron in its 5'-proximal protein coding sequence while the other two have none at this position; similarly, another gene has an intron in its 3'-proximal protein coding sequence which is not found in the other genes. All three genes are abundantly expressed together in Drosophila first, second, and early third instar larval stages and in adults, but they are not abundantly expressed in either embryonic, late third instar larval, or pupal stages. This gene family lies 11 X 10(3) bases away from another cluster containing four Drosophila larval cuticle protein genes plus a pseudogene. The cuticle genes are all abundantly expressed throughout third instar larval development. Thus, at least seven protein-coding genes and one pseudogene lie within 27 X 10(3) bases of DNA. Moreover, two small gene families can lie adjacent on a chromosome and exhibit different patterns of developmental regulation, even though individual genes within each clustered family are co-ordinately expressed.
在果蝇染色体区域44D内，已鉴定并定位了三个紧密聚集在8×10³个DNA碱基范围内的基因，并对该基因簇进行了全序列测定。这三个基因的DNA序列有55%至60%的同源性。其中一个基因在其5'近端蛋白质编码序列中含有一个内含子，而另外两个基因在该位置没有内含子；同样，另一个基因在其3'近端蛋白质编码序列中有一个内含子，而其他基因中未发现。这三个基因在果蝇的第一、第二和早期第三龄幼虫阶段以及成虫中共同大量表达，但在胚胎、晚期第三龄幼虫或蛹期均不大量表达。这个基因家族位于另一个基因簇11×10³个碱基之外，后者包含四个果蝇幼虫表皮蛋白基因和一个假基因。这些表皮蛋白基因在整个第三龄幼虫发育过程中均大量表达。因此，在27×10³个DNA碱基范围内至少存在七个蛋白质编码基因和一个假基因。此外，两个小基因家族可以相邻位于一条染色体上，并表现出不同的发育调控模式，尽管每个成簇家族中的单个基因是协同表达的。
