Cloning, expression, and characterization of a gene encoding the human angiotensin II type 1A receptor.

The human angiotensin II (AII) type 1a receptor gene and its upstream control sequence has been cloned from a human leukocyte genomic library. The promoter element CAAT and TATA sequences were found at -602 and -538, respectively, upstream from the translational initiation site. The deduced protein sequence is homologous to rat and bovine AT1a receptors (94.7% and 95.3% identity). The expressed gene exhibited high-affinity AII and Dup753 binding and was functionally coupled to inositol phosphate turnover. Northern analysis of human tissues showed AT1 receptor mRNA expression in placenta, lung, heart, liver, and kidney. Using 5' untranslated and coding sequence as probes in a Southern blot analysis, it was established that another AT1 subtype exists in the human genome.     

Genomic organization and regulation of a human 7-helix transmembrane receptor which is expressed in pulmonary epithelial cells and induced in hypoxia

The genetic, regulatory, and tissue-specific characterization of G-protein-coupled receptors is substantial since it contributes to the identification of the natural ligand which may influence basic physiological processes and cell function. Here we explored the genomic structure of a human orphan seven-transmembrane receptor which presents the human homologue of a receptor which has been controversially identified as a rat adrenomedullin receptor subtype. Based on the cDNA sequence a 3.4 kb genomic DNA fragment was isolated. Sequencing of the fragment and comparison studies revealed an intron of 544 bp in the 5' untranslated region, followed by a second exon encoding the receptor protein of 404 amino acids. The gene is localized on chromosome 12q. The 5' regulatory region contains several SP1, AP2, and CAAT sites as well as hypoxia responsive elements (HRE) both in the 5' and 3' regulatory region. RT-PCR with intron spanning primers demonstrated mRNA signals in various tissues, especially in lung. Characterizing the histological expression pattern in lung sections by nonisotopic in situ hybridization, a strong signal of receptor mRNA was identified in pulmonary epithelial cells of bronchi and alveoli. Analysis of the two human pulmonary epithelial cell lines, H23 and A549, showed significant mRNA induction of this receptor subtype in hypoxia.     

Nucleotide sequence analysis of the cloned salmon preproinsulin cDNA

A cDNA library was constructed using polyadenylated RNA from salmon (Oncorhynchus keta) Brockmann bodies, plasmid vector pBR322, and in vitro recombinant DNA techniques. Insulin-related clones were identified with a cDNA probe generated from the same RNA and enriched for insulin sequences. Two recombinants were shown to contain the nucleotide sequence of the entire coding region and parts of the 5' and 3' untranslated regions. The salmon preproinsulin mRNA is about 760 nucleotides long, 315 of which code for the protein, while about 190 and 200 nucleotides belong to the 5' and 3' flanking regions, respectively. Comparison of the nucleotide sequences of salmon insulin mRNA with those from other species reveals that sequence conservation is limited to the regions coding for the B and A peptides and two segments of the signal peptide. The C-peptide region exhibits no significant sequence homology with the C-peptides of other vertebrates. The 5' and 3' untranslated regions of the salmon preproinsulin mRNA are homologous only with the anglerfish mRNA, whereas there is no evident homology with those of birds and mammals. In addition to establishing the sequence of the preproinsulin mRNA, cloned salmon insulin cDNA provides a specific probe for the analysis and isolation of genomic DNA fragments containing insulin genes.     

Isolation and characterization of cDNA clones for human skeletal muscle alpha actin.

Two cDNA libraries corresponding to polyA+ RNA from human adult skeletal muscle have been constructed by cloning in the PstI site of pBR322. Skeletal alpha actin cDNA clones have been isolated and characterized. Three of these plasmids have overlapping inserts which together contain the complete 5' non-coding and protein-coding region and part of the 3' untranslated region. Determination of the sequence of the cloned cDNA confirms the complete conservation in human of the amino-acid sequence of skeletal alpha actin compared to the rabbit or rat proteins. The 5' untranslated region, but not the 3' untranslated region, shows good homology with the corresponding one in the rat gene. Analysis of changes at silent sites within the protein-coding region suggests that the divergence of skeletal and cardiac alpha actin took place much earlier than the mammalian radiation. The plasmids described here have been used as probes to detect the homologous gene among the about thirty actin sequences present in the human genome.     

Molecular cloning and the complete nucleotide sequence of the creatine kinase-M cDNA from chicken.

The nucleotide sequence of creatine kinase-M (CK-M) cDNA clones has been determined. It includes the entire coding region of 381 amino acids in addition to 5' and 3' untranslated regions. A comparison with a partial sequence from rat CK-M reveals 84% nucleotide sequence homology in the coding region but divergence in the 3' untranslated region. The amino acid sequence is 94% conserved between chicken and rat. Hybridization to RNA immobilized on filters indicates homology between the CK-M 3' untranslated region and additional muscle specific RNA species. The coding region hybridizes only to CK-M RNA.     

The sequences of rabbit kappa light chains of b4 and b5 allotypes differ more in their constant regions than in their 3'' untranslated regions.

We report the sequence of a cDNA clone encoding the entire variable and constant regions of a rabbit kappa light chain of b5 allotype. The deduced amino acid sequence of the variable region (positions 1-95) is 86% homologous to that of a b4 light chain protein [BS-1) (1) but the b4 and b5 constant regions are only 74% homologous. Comparison of this DNA sequence to that of a cDNA clone encoding a b4 constant region shows that the kappa allotypes b4 and b5 have diverged significantly more in their coding region than in the 3' untranslated regions (86% vs 96% nucleotide sequence homologies). This implies either a function for the 3' untranslated region with evolutionary pressures to conserve or an accelerated divergence of the coding regions.     

Characterization and nucleotide sequence of the gene for the common alpha subunit of the bovine pituitary glycoprotein hormones.

The gene coding for the common alpha subunit of the bovine pituitary glycoprotein hormones was isolated from a bovine genomic library. The gene spans roughly 16.5 kbp, contains three intervening sequences, and codes for a message of approximately 730 nucleotides. The complete coding region of the gene was sequenced as well as 315 nucleotides of 5' flanking sequence and the entire intron C. Only a single base difference was found when the sequence of the gene was compared with that of the cDNA. Genomic blotting experiments suggest the presence of a single alpha subunit gene. Comparison of the bovine and human alpha subunit genes indicated that the high level of homology observed in the coding regions has been maintained throughout the 5' and 3' untranslated regions, and at least 90 nucleotides of the 5'flanking regions. Additionally, there is an 18 base pair sequence present in both the 5' flanking and 5' untranslated regions of the gene that is homologous to a region of the chick ovalbumin gene. This ovalbumin sequence has been suggested as a binding site for the progesterone receptor-complex.     

Isolation and sequence analysis of cDNA clones coding for rat skeletal muscle creatine kinase

A series of cDNA clones corresponding to 1494 bases of rat muscle creatine kinase mRNA has been isolated and characterized. The identity of these clones has been confirmed by DNA sequence analysis and by comparison of the predicted amino acid sequence with that determined for the purified protein. The cDNA sequence accounts for the entire coding sequence of the creatine kinase protein in addition to the complete 3' untranslated region and 68 bases of 5' noncoding region. Sequences corresponding to the active site region of the protein, the initiation codon, the termination codon, and poly(A) addition signal have been identified.     

Complete amino acid sequence of human cartilage link protein (CRTL1) deduced from cDNA clones and chromosomal assignment of the gene

Little is known about the primary amino acid structure of human cartilage link protein (CRTL1). We screened a human genomic library with a cDNA encoding the 3' untranslated region and the adjoining B1 domain of chicken link protein. One clone was isolated and characterized. A 3.5-kb EcoRI-KpnI fragment from this genomic clone that contains the human B1 exon was used to map the gene to chromosome 5q13----q14.1. The same fragment was used to screen a cDNA library prepared from mRNA of Caco-2, a human colon tumor cell line. Two overlapping clones were isolated and shown to encode all of CRTL1. The deduced amino acid sequence is 354 residues long. The amino acid sequence shows a striking degree of identity to the porcine (96%), rat (96%), and chicken (85%) link protein sequences. Furthermore, there is greater than 86% homology between the 3' untranslated region of the genes encoding human and porcine link proteins. These results indicate that there has been strong evolutionary pressure against changes in the coding and 3' untranslated regions of the gene encoding cartilage link protein.