Isolation and molecular characterization of the porcine transforming growth factor beta type I receptor (TGFBR1) gene

The transforming growth factor beta (TGF beta) family is essential for normal growth and development of different organ systems. Here we describe the isolation and molecular characterization of the full-length cDNA and the determination of the genomic DNA sequence of the porcine TGFBR1 gene. The full-length TGFBR1 cDNA 1813 bp contains an open reading frame (ORF) of 1512 bp encoding a TGFBR1 protein of 503 amino acids with a calculated molecular weight (Mw) of 56.4 kDa. A BAC clone harboring the porcine TGFBR1 gene was isolated and sequenced. The results of genomic and cDNA sequences of the porcine TGFBR1 gene demonstrated that it spans a transcription unit of 62,182 bp consisting of nine exons ranging from 125 to 354 bp, and eight introns ranging from 1003 to 29,441 bp. A shorter porcine TGFBR1 isoform resulting from the alternative splicing of exon 7 in porcine TGFBR1 cDNA was detected. The shorter TGFBR1 isoform contained a 1140 bp ORF encoding 379 amino acids with a calculated Mw of 41.7 kDa. The core promoter of porcine TGFBR1 gene lacks a TATA box but contains GC boxes and CAAT boxes. Multiple transcription initiation and termination sites were identified in untranslated regions (UTR) resulting in the size of 5'-UTR varying from 15 to 62 bp, and the length of 3'-UTR varying from 169 to 228 bp. Quantitative real time PCR results showed that the TGFBR1 transcript was ubiquitously expressed in all tissues examined (i.e. fat, adrenal, brain, spinal cord, muscle, mandibular lymph node, thymus, bone marrow, uterus, spleen, testis, kidney, liver, and ovary). A total of eighty-five gene polymorphisms (77 SNPs and 8 indels) were detected in the porcine TGFBR1 gene by utilizing a panel of DNA from eight diversified pig breeds (Yorkshire, Chinese Meishan, Berkshire, Duroc, Hampshire, Landrace, Large White and Pietrain). The minor allele frequencies of these nucleotide variations varied from 0.13 to 0.5 with an average of 0.26. In addition, seventeen microsatellites were identified throughout the genomic sequence of the porcine TGFBR1 gene.