Bigby T D, Hodulik C R, Arden K C, Fu L
Department of Medicine, University of California, San Diego, USA.
Mol Med. 1996 Sep;2(5):637-46.
Cysteinyl leukotrienes (LT) are mediators involved in inflammatory and allergic disorders LTC4 synthase catalyzes the first committed step in the synthesis of these inflammatory mediators, and its cellular distribution appears to be unique.
A human genomic library was screened by polymerase chain reaction (PCR) with primers that were designed based on the reported cDNA sequence for the LTC4 synthase gene. The gene was identified in one clone by Southern blotting of restriction enzyme digests, subcloning of fragments containing regions of interest, and DNA sequencing of these subclones. The transcription initiation site was determined by primer extension analysis. Chromosome location was determined by fluorescent in situ hybridization and screening of somatic cell hybrids by PCR.
The LTC4 synthase gene is approximately 2.5 kb in length, consisting of five exons (136, 100, 71, 82, and 257 bp, respectively) and four introns (1,447, 102, 84, and 230 bp, respectively). Transcription initiation occurs at a single site 78 bp upstream of the coding region. The 5'-flanking region contains neither a TATA nor a CAAT box. The first 1 kb of the 5'-flanking region, however, contains putative DNA binding motifs for SP-1, AP-1, AP-2, ets factors, and CREB/ATF. A STAT binding motif is present in the first intron. The LTC4 synthase gene is located in the distal region of the long arm of chromosome 5 in 5q35.
The LTC4 synthase gene does not contain elements of a typical regulated gene and may therefore contain novel regulatory elements. This gene is also located in a region on chromosome 5 that appears to play a role in allergic and inflammatory disorders, such as asthma.
半胱氨酰白三烯（LT）是参与炎症和过敏性疾病的介质。LTC4合酶催化这些炎症介质合成的第一步关键反应，其细胞分布似乎具有独特性。
用基于已报道的LTC4合酶基因cDNA序列设计的引物，通过聚合酶链反应（PCR）筛选人基因组文库。通过对限制性酶切片段进行Southern印迹、对含感兴趣区域的片段进行亚克隆以及对这些亚克隆进行DNA测序，在一个克隆中鉴定出该基因。通过引物延伸分析确定转录起始位点。通过荧光原位杂交和PCR筛选体细胞杂种确定染色体定位。
LTC4合酶基因长度约为2.5 kb，由五个外显子（分别为136、100、71、82和257 bp）和四个内含子（分别为1447、102、84和230 bp）组成。转录起始于编码区上游78 bp处的单个位点。5'侧翼区既没有TATA盒也没有CAAT盒。然而，5'侧翼区的前1 kb包含SP-1、AP-1、AP-2、ets因子和CREB/ATF的假定DNA结合基序。第一个内含子中存在一个STAT结合基序。LTC4合酶基因位于5号染色体长臂的远端区域5q35。
LTC4合酶基因不包含典型调控基因的元件，因此可能包含新的调控元件。该基因也位于5号染色体上一个似乎在过敏性和炎症性疾病（如哮喘）中起作用的区域。
