Tissue and species distribution of mRNA encoding two ADP-ribosylation factors, 20-kDa guanine nucleotide binding proteins

Cholera toxin catalyzed ADP-ribosylation of Gs alpha, the stimulatory guanine nucleotide binding protein of the adenylyl cyclase system, is enhanced by approximately 20-kDa guanine nucleotide binding proteins, termed ADP-ribosylation factors or ARFs. ARF is an allosteric activator of the A1 catalytic protein of the toxin. Bovine ARF cDNA clones, ARF-1 isolated from adrenal (Sewell & Kahn, 1988) and ARF-2B from retina (Price et al., 1988), exhibit nucleotide and deduced amino acid sequences that are 80% and 96% identical, respectively, in the coding region. To determine tissue and species distribution of ARF-like mRNAs, bovine ARF-2B and human ARF-1 cDNAs and 30- or 48-base oligonucleotide probes that distinguish between ARF-1 and ARF-2B cDNAs in coding and 3'-untranslated regions were used for Northern analysis of poly(A+) RNA from different tissues and species. On the basis of hybridization with specific oligonucleotide probes, all bovine tissues contained mRNAs of 1.7 and 2.1 kb that were related to ARF-1 and ARF-2B, respectively. Northern analysis of brain poly(A+) RNA from different species with ARF-2B and ARF-1 cDNAs at low stringency demonstrated several bands varying in size from 0.9 to 3.7 kb. A 1.7-kb band consistently hybridized with an ARF-1 30-base coding-region probe but not with a probe for the 3'-untranslated region. Similar ARF-2B oligonucleotide probes did not hybridize with rat, mouse, rabbit, or human brain mRNA. Cleavage of ARF-2B cDNA with PvuII generated two fragments, one containing coding and the other 3'-noncoding region.(ABSTRACT TRUNCATED AT 250 WORDS)     

Xenopus liver ferritin H subunit: cDNA sequence and mRNA production in the liver following estrogen treatment

In vitro translation of liver mRNA from estrogen-treated Xenopus frogs yields two abundant polypeptides in the range of 20 kDa. DNA clones for one of these translation products were isolated and shown to be complementary to mRNA for the heavy subunit of ferritin. The predicted Xenopus amino acid sequence shares about 86% identity with the ferritin heavy chain from bullfrogs and about 70% identity with the comparable mammalian and avian proteins. Clone identity was confirmed by hybridization selection followed by in vitro translation into translation products of 19.5-20 kDa. The nearly full-length cDNA clone, termed XlferH1, comprises 868 nucleotides plus 22 adenosines of the poly(A) tail, including 134 nucleotides of the 5'-untranslated region, a 528-base coding region for 176 amino acids, and a 206-nucleotide 3'-untranslated region. The clone lacks 22 nucleotides from the 5' end of the mRNA. The level of ferritin mRNA in the liver of estrogen-treated frogs was determined over time. The amount of this mRNA relative to total RNA decreased about 3-fold 14 days after estradiol-17 beta was administered. However, the hormone also elevated total RNA in the liver about 24-fold. Hence, the total ferritin mRNA content of the liver increased to about 8 times its initial amount. This pattern of gene expression was very similar to that for serum retinol binding protein. The estrogen induction of these two mRNAs appeared to parallel the overall stimulation of hepatic RNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular cloning of rat insulin-like growth factor I complementary deoxyribonucleic acids: differential messenger ribonucleic acid processing and regulation by growth hormone in extrahepatic tissues

Two classes of insulin-like growth factor I (IGF-I) cDNAs were isolated from an adult rat liver library using a human IGF-I cDNA probe. The two types of rat IGF-I cDNA differed by the presence or absence of a 52-base pair insert which altered the derived C-terminal amino acid sequence of the E peptide, but not the 3'-untranslated region or the sequence coding for the mature IGF-I protein. When probes derived from these cDNA clones were hybridized to Northern blots of rat mRNA, specific bands of 8.6, 2.1, and 1.0-1.4 kilobases were seen. Hybridization to poly(A)+ RNA from various tissues from GH-treated and control rats demonstrated an increase in IGF-I mRNA due to GH treatment in all tissues examined.     

Isolation and characterization of cDNA clones for plant cyclins.

We have isolated and sequenced a carrot cDNA and two soybean cDNAs encoding mitotic cyclin homologs. The soybean clones were derived from nearly identical cognate genes. The carrot cyclin and soybean cyclins were slightly more similar to A-type and B-type cyclins thus far defined, respectively. However, they had divergent amino acid sequences in the portion that is most highly conserved in known cyclins and we could not easily include them in either of the phylogenetic types. Since the homology between carrot and soybean cyclins was low, each of them might define a novel and distinct type. The mRNA of carrot cyclin, 1.5 kb in length, was expressed concomitant with somatic embryogenesis of cultured cells. Expression of soybean cyclin mRNAs, 1.6 kb in length, was localized in proliferating parts of seedlings. As in the case of cyclin genes of marine invertebrates, microinjection of a synthetic mRNA for the soybean cyclin induced the maturation of Xenopus oocytes. Other cyclin genes may be present because, on Southern blot analysis of soybean genomic DNA, the isolated soybean cDNA probe hybridized with additional genes under low stringency.     

Primary structure of human, chicken, and Xenopus laevis p11, a cellular ligand of the Src-kinase substrate, annexin II.

The p11 protein is a member of the S-100 family of Ca(2+)-binding proteins and serves within the cell as a ligand of the tyrosine kinase substrate, annexin II. To obtain more structural information on this molecule, we have isolated and characterized p11 cDNA clones from several different species. A comparison of the deduced amino acid (aa) sequences reveals that mammalian and avian p11 are highly similar (at least 90% identical at the aa level), whereas p11 from Xenopus laevis shows a considerable degree of sequence variation (the aa sequence identity drops to approx. 60% when compared to mammalian or chicken p11). Interestingly, the C-terminal 18 aa, which are unique to p11 within the S-100 family, show a relatively high conservation among species. This high evolutionary conservation is in line with a structurally and/or functionally important role of this C terminus, e.g., in annexin II binding.