scholarly journals Isolation and characterization of calmodulin genes from Xenopus laevis.

1984 ◽  
Vol 4 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Y H Chien ◽  
I B Dawid

Two cDNAs derived from Xenopus laevis calmodulin mRNA have been cloned. Both cDNAs contain the complete protein-coding region and various lengths of untranslated segments. The two cDNAs encode an identical protein but differ from each other by 5% nucleotide substitutions. The 5' and 3' untranslated regions, to the extent available, are highly homologous between the two cDNAs. The predicted sequence of X. laevis calmodulin is identical to that of vertebrate calmodulins from mammals and chickens and shows one substitution compared with electric eel calmodulin. Genomic DNA sequences homologous to each of the two cDNA clones have been isolated and were shown to account for the major calmodulin-coding DNA sequences in X. laevis. These data suggest that X. laevis carries two active, nonallelic calmodulin genes. Although no complete analysis has been carried out, it appears that the X. laevis calmodulin genes are interrupted by at least four introns. The relative concentrations of calmodulin mRNA have been estimated in different embryonic stages and adult tissues and found to vary by up to a factor of 10. The highest levels of calmodulin mRNA were found in ovaries, testes, and brains. In these three tissues, the two calmodulin genes appear to be expressed at approximately equal levels.

1984 ◽  
Vol 4 (3) ◽  
pp. 507-513
Author(s):  
Y H Chien ◽  
I B Dawid

Two cDNAs derived from Xenopus laevis calmodulin mRNA have been cloned. Both cDNAs contain the complete protein-coding region and various lengths of untranslated segments. The two cDNAs encode an identical protein but differ from each other by 5% nucleotide substitutions. The 5' and 3' untranslated regions, to the extent available, are highly homologous between the two cDNAs. The predicted sequence of X. laevis calmodulin is identical to that of vertebrate calmodulins from mammals and chickens and shows one substitution compared with electric eel calmodulin. Genomic DNA sequences homologous to each of the two cDNA clones have been isolated and were shown to account for the major calmodulin-coding DNA sequences in X. laevis. These data suggest that X. laevis carries two active, nonallelic calmodulin genes. Although no complete analysis has been carried out, it appears that the X. laevis calmodulin genes are interrupted by at least four introns. The relative concentrations of calmodulin mRNA have been estimated in different embryonic stages and adult tissues and found to vary by up to a factor of 10. The highest levels of calmodulin mRNA were found in ovaries, testes, and brains. In these three tissues, the two calmodulin genes appear to be expressed at approximately equal levels.


Cell ◽  
1984 ◽  
Vol 38 (3) ◽  
pp. 667-673 ◽  
Author(s):  
Michael Levine ◽  
Gerald M. Rubin ◽  
Robert Tjian

1987 ◽  
Vol 7 (5) ◽  
pp. 1873-1880
Author(s):  
H Nojima ◽  
K Kishi ◽  
H Sokabe

We have observed three calmodulin mRNA species in rat tissues. In order to know from how many expressed genes they are derived, we have investigated the genomic organization of calmodulin genes in the rat genome. From a rat brain cDNA library, we obtained two kinds of cDNAs (pRCM1 and pRCM3) encoding authentic calmodulin. DNA sequence analysis of these cDNA clones revealed substitutions of nucleotides at 73 positions of 450 nucleotides in the coding region, although the amino acid sequences of these calmodulins are exactly the same. DNA sequences in the 5' and 3' noncoding regions are quite different between these two cDNAs. From these results, we conclude that they are derived from two distinct bona fide calmodulin genes, CaMI (pRCM1) and CaMII (pRCM3). Total genomic Southern hybridization suggested four distinct calmodulin-related genes in the rat genome. By cloning and sequencing the calmodulin-related genes from rat genomic libraries, we demonstrated that the other two genes are processed pseudogenes generated from the CaMI (lambda SC9) and CaMII (lambda SC8) genes, respectively, through an mRNA-mediated process of insertions. Northern blotting showed that the CaMI gene is transcribed in liver, muscle, and brain in similar amounts, whereas the CaMII gene is transcribed mainly in brain. S1 nuclease mapping indicated that the CaMI gene produced two mRNA species (1.7 and 4 kilobases), whereas the CaMII gene expressed a single mRNA species (1.4 kilobases).


1987 ◽  
Vol 7 (8) ◽  
pp. 2933-2940
Author(s):  
H Honkawa ◽  
W Masahashi ◽  
S Hashimoto ◽  
T Hashimoto-Gotoh

A number of deletion mutants were isolated, including 5', 3', and internal deletions in the 5'-flanking region of the human cellular oncogene related to the Harvey sarcoma virus (c-H-ras), and their transforming activities were examined in NIH 3T3 cells. DNA sequences which could not be detected without losing transforming activity were localized to a relatively short stretch upstream of the region which showed homology to the 5'-flanking region of v-H-ras oncogene. S1 nuclease analysis indicated that there were two clusters of mRNA start sites at positions that were about 1,371 and 1,298 base pairs upstream of the first coding ATG. The minimum region required for promoter function was estimated to be a 51-base-pair-long (or less) DNA segment. The promoter was GC rich (78%) and did not contain the consensus sequences that are usually observed in PolII-directed promoters but contained a GC box within which one of the mRNA start sites was included. In addition, two sets of positive and negative elements seemed to be located between the promoter and the protein-coding region, which appeared to influence positively and negatively, respectively, the efficiency of transformation with the c-H-ras oncogene.


Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 873-884 ◽  
Author(s):  
Y Ogihara ◽  
T Terachi ◽  
T Sasakuma

Abstract The nucleotide divergence of chloroplast DNAs around the hot spot region related to length mutation in Triticum (wheat) and Aegilops was analyzed. DNA sequences (ca. 4.5 kbp) of three chloroplast genome types of wheat complex were compared with one another and with the corresponding region of other grasses. The sequences region contained rbcL and psaI, two open reading frames, and a pseudogene, rpl23' (pseudogene for ribosomal protein L23) disrupted by AT-rich intergic spacer regions. The evolution of these genes in the closely related wheat complex is characterized by nonbiased nucleotide substitutions in terms of being synonymous/nonsynonymous, having A-T pressure transitions over transversions, and frequent changes at the third codon position, in contrast with the gene evolution among more distant plant groups where biased nucleotide substitutions have frequently occurred. The sequences of these genes had diverged almost in proportion to taxonomic distance. The sequence of the pseudogene rpl23' changed approximately two times faster than that of the coding region. Sequence comparison between the pseudogene and its protein-coding counterpart revealed different degrees of nucleotide homology in wheat, rice and maize, suggesting that the transposition timing of the pseudogene differed and/or that different rates of gene conversion operated on the pseudogene in the cpDNA of the three plant groups in Gramineae. The intergenic spacer regions diverged approximately ten times faster than the genes. The divergence of wheat from barley, and that from rice are estimated based on the nucleotide similarity to be 1.5, 10 and 40 million years, respectively.


Genetics ◽  
1984 ◽  
Vol 106 (4) ◽  
pp. 735-749
Author(s):  
Gerard Zurawski ◽  
Michael T Clegg ◽  
Anthony H D Brown

ABSTRACT Analysis of a 2175-base pair (bp) SmaI-HindIII fragment of barley chloroplast DNA revealed that rbcL (the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase) and atpB (the gene for the β subunit of ATPase) are transcribed divergently and are separated by an untranscribed region of 155-166 bp. The rbcL mRNA has a 320-residue untranslated leader region, whereas the atpB mRNA has a 296- to 309-residue leader region. The sequence of these regions, together with the initial 113 bp of the atpB-coding region and the initial 1279 bp of the rbcL-coding region, is compared with the analogous maize chloroplast DNA sequences. Two classes of nucleotide differences are present, substitutions and insertions/deletions. Nucleotide substitutions show a 1.9-fold bias toward transitions in the rbcL-coding region and a 1.5-fold bias toward transitions in the noncoding region. The level of nucleotide substitutions between the barley and maize sequences is about 0.065/bp. Seventy-one percent of the substitutions in the rbcL-coding region are at the third codon position, and 95% of these are synonymous changes. Insertion/deletion events, which are confined to the noncoding regions, are not randomly distributed in these regions and are often associated with short repeated sequences. The extent of change for the noncoding regions (about 0.093 events/bp) is less than the extent of change at the third codon positions in the rbcL-coding region (about 0.135 events/bp), including insertion/delection events. Limited sequence analysis of the analogous DNA from a wild line (Hordeum spontaneum) and a primitive Iranian barley (H. vulgare) suggested a low rate of chloroplast DNA evolution. Compared to spinach chloroplast DNA, the barley rbcL-atpB untranslated region is extremely diverged, with only the putative rbcL promoters and ribosome-binding site being extensively conserved.


2018 ◽  
Vol 7 (1.9) ◽  
pp. 167
Author(s):  
Bipin Nair B J ◽  
Rahul Reghunath

The protein coding and functional regions in DNA sequences has become an exciting task in bioinformatics. In particular, the coding region has a 3-base periodicity, which helps for exon identification. Many signal processing tools and techniques have been successfully applied to identify tasks, but still need to be improved in this direction. In our work, we employ ANN classifier to predict coding and functional region of proteinin human embryo cell protein in first trimester, and evaluate their performances according to the comparison energy levels of coding region. The obtained from the threshold energy level, results show that in a box plot finally predict the mutation.


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