Alternative RNA splicing of the murine alpha A-crystallin gene: protein-coding information within an intron

The eye lens contains a structural protein (alpha-crystallin), composed of two homologous primary gene products, alpha A2 and alpha B2. In certain rodents, there is another minor alpha-crystallin polypeptide, alpha Ains, which is identical to alpha A2 except for a 22 amino acid insert between residues 63 and 64 of the alpha A2 chain. Here we show that the mouse contains a single alpha A-crystallin gene, which has a 1376 bp intron separating codons 63 and 64 of the alpha A2-crystallin mRNA. A sequence encoding a 23 amino acid insert peptide was found 266 bp into the intron. The nucleotide borders of this sequence deviate from the AGGT consensus sequence. The DNA sequence encoding the insert peptide hybridizes to a cytoplasmic 14S RNA, demonstrating that it is transcribed in the lens. We propose that the murine alpha A2-crystallin gene generates both the alpha A2 and the alpha Ains mRNAs by alternative splicing.     

Construction and identification of a cDNA clone for human type II procollagen mRNA.

Double-stranded cDNA was constructed for poly(A)-containing RNA isolated from foetal human articular cartilage known to contain small amounts of pro alpha 1 (II) collagen mRNA. A 585 base pair PstI-EcoRI cDNA fragment was isolated and cloned into plasmid pBR322. A resulting recombinant plasmid pHCAR1 was shown to hybridize specifically to a 5.4 kilobase mRNA in cartilage but not in calvarial RNA. Definite identification of clone pHCAR1 was based on sequence analysis; marked homology with the corresponding chick gene and complete agreement with the human gene sequences available were observed.     

Gain and loss of an intron in a protein-coding gene in Archaea: the case of an archaeal RNA pseudouridine synthase gene

Background  

We previously found the first examples of splicing of archaeal pre-mRNAs for homologs of the eukaryotic CBF5 protein (also known as dyskerin in humans) in Aeropyrum pernix, Sulfolobus solfataricus, S. tokodaii, and S. acidocaldarirus, and also showed that crenarchaeal species in orders Desulfurococcales and Sulfolobales, except for Hyperthermus butylicus, Pyrodictium occultum, Pyrolobus fumarii, and Ignicoccus islandicus, contain the (putative) cbf5 intron. However, the exact timing of the intron insertion was not determined and verification of the putative secondary loss of the intron in some lineages was not performed.     

Analysis of three restriction fragment length polymorphisms in the human type II procollagen gene.

Cloned genomic DNA sequences corresponding to various regions of the human type II procollagen gene were used to analyze the DNA from 78 normal volunteers. Southern hybridization experiments detected polymorphic HindIII, BamHI, and EcoRI sites. The presence of the polymorphic HindIII site results in a 7.0-kilobase (kb) band, and the absence of this site results in a 14.0-kb band. When present, the BamH1 polymorphic site yields a 4.8-kb band, and when absent, yields a 7.2-kb band. The presence of the EcoRI polymorphic site results in a 3.7-kb band, and its absence results in a 7.0-kb band. Each polymorphic site was mapped. Analyses of the data demonstrated that the sites are present in overall gene frequencies of .39 for HindIII, .04 for BamHI, and .02 for EcoRI. Gene frequencies of the polymorphic sites were also studied with respect to race. The polymorphic sites are present in a Hardy-Weinberg distribution in the study population. Study of an extended family demonstrated that the segregation of the HindIII polymorphic site is consistent with Mendelian inheritance.     

Isolation and characterization of genomic clones corresponding to the human type II procollagen gene.

A recombinant human DNA library was screened using probes corresponding to the chick alpha 1 (II) procollagen gene. This resulted in the isolation of 2 different genomic clones, LgHCol(II)a and LgHCol(II)b. LgHCol(II)a was identified as corresponding to the alpha 1(II) gene by comparative hybridization and DNA sequence analysis. DNA sequence established that LgHCol(II)a extends at least from amino acid 694 of the triple helix through 54 amino acids of the COOH-propeptide. Hybridization with a probe containing only the exon at the 3' end of the chicken gene suggests that the clone contains the 3' end of the human gene. Thus LgHCol(II)a contains approximately 40% of the coding sequences of the human type II collagen gene.