The Structure and Sequence Analysis of TLR4 Gene in Cattle

Toll-like receptor 4 (TLR4) is essential for initiating the innate response to lipopolysaccharide (LPS) from Gram-negative bacteria by acting as a signal transducting receptor.In order to help in investigating TLR4 as a candidate disease-resistance gene in cows,we isolated the cDNA (GenBank accession no.DQ839566) by RT-PCR and rapid amplification of cDNA ends (RACE) experiments and analyzed the sequence characters by bioinformatics.The results showed that cattle TLR4 gene about 3 739 bp contains an open reading frame of 2 526 bp encoded 841 amino acids (aa),470 bp 5" untranslated region (UTR),and 743 bp 3' UTR.Tissue expression profile by RT-PCR indicated that TLR4 gene expresses in mammary glands,liver,muscle,duodenum,fats,uterus,kidneys,hearts,lungs,pancreas,and ovary.TLR4 protein domain predicted by bioinformatics consists of signal peptide,transmembrane helices domain,3 sorts of leucine-rich repeat domains (LRR,LRR-TYP,and LRRCT),and a toll-interleukinl-resistance domain (TIR).Leucine-rich repeat domains were related with recognizing a broad of pathogen-associated molecular patterns (PAMP) from pathogen,and TIR domain for downstream signaling transduction was most conservative (98% identify) than other domains after alignment of protein from ovine,porcine,human,and mouse.In addition,a 470 bp 5'-flanking region sequence was amplified by PCR,and 15 putative DNA binding sites were predicted,but this sequence lacks TATA box,CCAAT character,and GC-rich regions.