Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four cDNA probes for the human major histocompatibility complex (MHC) were used to investigate the sheep MHC, in conjunction with serological typing for ovine lymphocyte antigen (OLA). Lymphocytes from a family (two parents and five offspring) of Romanov sheep were subjected to genomic DNA digestion by the restriction endonuclease Eco RI, followed by gel electrophoresis. A single Southern blot representing all seven individuals was then consecutively hybridized with the class I, alpha-DC, beta-DR, and C4 probes, which were originally designed to identify HLA class I, class II (DC and DR), and C4 products, respectively. Using each of the three class I/class II probes, several bands showing DNA polymorphism were detected. The segregation of these bands in the five offspring exactly paralleled the OLA haplotype segregation established by serological typing. A further eight individuals carrying haplotypes which were phenotypically identical to those in the above-mentioned family showed bands in the corresponding positions when tested with the same three probes. Using the C4 probe, no polymorphism was detected in these fifteen individuals.
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PMID:Analysis of the sheep MHC using HLA class I, II, and C4 cDNA probes. 299 30

The extent of the C2 locus in the HLA class III region has been determined by Southern blotting techniques and by DNA sequence analysis. The gene is 18 kb in length and therefore provides a marked contrast to the adjacent factor B gene of 6 kb. A novel restriction fragment length polymorphism (RFLP) has been identified using the endonuclease Sst I and a genomic probe derived from the 5' region of the C2 gene. Four variants have been detected in a sample of unrelated individuals with haplotypes carrying the C2C allele. Further analysis using C2 and factor B cDNA probes has determined the relationship between this and the other RFLPs previously identified in this region of the genome. Together, the three polymorphisms identified so far make the subdivision of previously indistinguishable haplotypes possible. They therefore constitute a series of markers which increase the resolution of genetic variation in the C2 locus and they may be important in studies of diseases associated with this region of the major histocompatibility complex.
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PMID:DNA polymorphism of the C2 locus. 299 31

The gene coding for properdin factor Bf is located in the human major histocompatibility complex and is closely linked to the genes coding for the complement components C2 and C4. Recently, by Southern blotting techniques, a restriction fragment length polymorphism was identified using the endonuclease Taq I, which subdivides haplotypes carrying the F allele of factor Bf. The F allotype has also been subdivided at the protein level by isoelectric focusing into two subtypes Fa and Fb. We have investigated the DNA of 41 healthy unrelated individuals with known BfF subtypes using the 2.3 kb factor Bf cDNA probe to determine if there is any correlation between the Taq I polymorphism and F subtype. We have found that in 23 individuals who carried the Fb subtype a 6.6 kb Taq I fragment was present. The remaining 18 individuals carried the Fa subtype and showed only the 4.5 kb Taq I fragment on Southern blotting (P = 10(-12). This striking correlation (r = 1) between the Fb protein and DNA polymorphism is surprising especially as the 4.5 kb and 6.6 kb Taq I fragments overlap the Bf and C2 genes and the polymorphic Taq I site is located within the C2 gene.
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PMID:A DNA restriction fragment length polymorphism in the complement region of the human MHC shows an absolute correlation with polymorphism of complement factor B(Bf) defined by isoelectric focusing. 301 98

The human major histocompatibility complex includes the DP, DQ, and DR subregions, each of which contains at least one alpha chain gene and two beta chain genes. The products of the alpha chain gene and a beta chain gene from a given subregion combine to form a heterodimer which is found predominantly on the surface of immunocompetent cells, and is essential for effective cell-cell interactions and the generation of an immune response. The beta chain of the DR molecule is highly polymorphic, and it is this polymorphism which is thought to be ultimately responsible for the specific immune responsiveness and disease predisposition conferred by different DR molecules. While the sequences of DR beta chains of the homozygous DR1 cells, homozygous DR2, homozygous DR4, DR3/w6 cells and DR4/w6 genotypes have been partially or completely characterized, no sequence is yet available for the DR beta chain from a homozygous DR5 cell. A cDNA library was therefore constructed from the Swei cell line homozygous for the DR5 haplotype. A beta chain clone was isolated, characterized, and sequenced. Comparison with previously published DR beta chain restriction endonuclease maps and nucleotide sequences demonstrated that this clone was a DR beta chain clone. Comparison of the deduced amino acid sequence with other DR beta chain amino acid sequences shows three regions of variability in the first external domain, corresponding to amino acid residues 9-13, 26-38, and 67-74. The sequence of each of these variable regions in the beta chain from DR5 cells was identical or nearly identical to the sequences of variable regions found in the beta chains of other DR haplotypes, supporting the notion of gene conversion as an evolutionary mechanism generating polymorphism. The second external domain, and transmembrane and intracytoplasmic regions show a high degree of sequence conservation.
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PMID:Complete characterization and sequence of an HLA class II DR beta chain cDNA from the DR5 haplotype. 345 44

The major histocompatibility complex of the rat (RT1) encodes the class II molecules involved with antigen presentation and cell to cell communication. The organization of these class II genes has been studied by Southern blot hybridization using genomic DNA from inbred and recombinant rat strains digested with various restriction endonuclease and hybridized under stringent conditions with probes for mouse class II and human class II genes. Analysis of the restriction fragment length polymorphisms has mapped the class II genes relative to each other. We have confirmed the order of the alpha- and beta-chain genes in the RT1.B region, mapped the RT1.D region relative to RT1.B and showed that it has alpha- and beta-chain loci, and identified a new HLA-DP-like locus, RT1.H, to the RT1.A side of RT1.B. The RT1.H alpha and RT1.H beta genes map to the region around the recombination point in R22, and there appears to be a hot spot of recombination in RT1.H. The H beta and D beta genes have high levels of polymorphism; B beta, B alpha, and H alpha have intermediate levels of polymorphism, and D alpha has a low level of polymorphism.
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PMID:Polymorphism and mapping of the class II genes in the rat: RT1.B, RT1.D, and RT1.H, a new DP-like region. 365 40

Factor B and C2 are structurally and functionally similar complement proteins encoded by genes that are closely linked within the class III region of the major histocompatibility complex (MHC). In this study, restriction endonuclease digestion of cosmid DNAs isolated from an H-2d murine genomic library indicated that the chromosomal organization of these two genes was similar in mouse to that in man. To further characterize their expression, cosmid DNAs encoding human and murine factor B and C2 were introduced into mouse L cells by DNA-mediated gene transfer. Factor B expression was demonstrated in cells transfected with either the human or the murine gene, but not in cells transfected with a control plasmid. Synthesis and secretion of factor B by L cells transfected with the human and murine cosmids was similar to that of human and murine cells in primary culture. An interspecies variation between human and murine factor B was identified and reproduced with extraordinary fidelity by the mouse fibroblast. In contrast, C2 RNA and protein were expressed by L cells alone and by L cells transfected with a control plasmid, as well as by L cells transfected with cosmids encoding human and murine complement genes. Expression of the transferred human C2 gene was demonstrated by the presence of a new distinct C2 RNA transcript and secretion of biologically active human C2. These results demonstrate the similarity of organization of the murine and human class III MHC regions. Expression of the two closely linked gene products, C2 and factor B, after DNA-mediated gene transfer provides a system for further analysis of regulation in both normal and deficient states.
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PMID:Expression of complement proteins C2 and factor B in transfected L cells. 385 Sep 3

A search for uncharacterized genes of the S region of the murine H-2 major histocompatibility complex was undertaken; a series of cosmid clones previously aligned by overlap hybridizations were used as radiolabeled probes. Sequences hybridizing with liver poly(A)+ RNA were found within a cosmid covering a region 3' to the C4-Slp gene (the gene encoding the hemolytically inactive isoform of the fourth component of serum complement). Radiolabeled, short cDNA complementary to liver poly(A)+ RNA was used to establish the transcriptional polarity of the newly detected gene and to define fragments containing its 3' end. DNA sequence analyses and comparisons with porcine peptides established that the gene encodes the enzyme steroid 21-hydroxylase (EC 1.14.99.10), a cytochrome P-450 often referred to as P-450(C21), whose major site of expression is the adrenal gland. Two copies of the P-450(C21) gene, very similar yet distinguishable by restriction endonuclease analysis, were found individually associated with C4 and C4-Slp, genes that encode isoforms of mouse fourth component of complement. One of the P-450(C21) genes is coamplified with C4-Slp in H-2w7, a haplotype carrying a rare elongation of the S region. Comparisons with other members of the P-450 gene family show that the P-450(C21) genes encode peptides of extraordinary evolutionary conservation. The detection of a liver transcript of P-450(C21) raises the issue of the specific metabolic role of this enzyme in this organ and may have implications for the interpretation of human congenital adrenal hyperplasia.
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PMID:Liver mRNA probes disclose two cytochrome P-450 genes duplicated in tandem with the complement C4 loci of the mouse H-2S region. 387 1

Cytotoxic T lymphocyte (CTL) recognition sites on class I major histocompatibility complex molecules have been investigated by several laboratories by using cloned genes expressed on mouse L cells by DNA-mediated gene transfer. Recombinant genes, constructed by restriction endonuclease treatment of cloned H-2Dd and Ld genes and exchange of the N and C1 exons (exon shuffling) have provided an additional tool. These hybrid H-2 molecules expressed on L cells have been used as targets to achieve more precise localization of site(s) recognized by allospecific and virus-specific CTLs. CTL systems were chosen that limit recognition to either the Dd or Ld alloantigen or to virus and Dd or Ld complexes. Using this approach, we were able to map essential restricting site(s) to the N and/or C1 domains. Additional evidence is presented that the cytoplasmic tail of H-2 may be involved in interactions with some viral antigens and effect the formation of an immunogenic complex.
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PMID:Cytotoxic T lymphocyte recognition of class I H-2 antigens after DNA-mediated gene transfer. 619 17

A cDNA clone known to code for a mouse histocompatibility (class I) antigen was found to contain a sequence specific for a subpopulation of H-2 genes. This unique sequence is located in the 3' non-coding region close to the stretch of poly(A) nucleotides. A subclone containing this fragment (pH-2d-5) has been used to select hybridizing mRNA. Translation of the mRNA in vitro shows that H-2Kd mRNA is selected. Southern blot analysis of DNA from congenic recombinant mice show that at least one gene containing this sequence is located at the K locus (region) of the major histocompatibility complex. This gene contains a 3.7-kb BglII and a 13-kb EcoRI restriction endonuclease fragment. This gene has been isolated from a genomic DNA library.
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PMID:Identification of an H-2Kd gene using a specific cDNA probe. 632 84

The rabbit cell line RL-5 was recently found to express only a single detectable major histocompatibility complex class I protein, in contrast to the multiple class I proteins expressed in cells of the mouse (K, D, and L) and human (A, B, and C). To clarify this difference in the rabbit major histocompatibility complex, we have begun an investigation of the class I genes expressed in the RL-5 cell line and here report the construction of 31 class I cDNA clones derived from RL-5 mRNA. Restriction endonuclease mapping has allowed classification of these clones into five groups, apparently representing five distinct class I mRNA transcripts. The sequence of a full-length cDNA from the predominant group (representing 26 of the 31 clones) reveals a typical class I structure, with an amino terminus that exactly matches the 36 amino terminal residues previously determined for the class I protein immunoprecipitated from RL-5. Complete sequence of a second distinct class I mRNA transcript was deduced from cDNA clones of the second largest group (representing two of the 31 clones). Although this transcript corresponds to a complete class I sequence, an anomaly in initiation sequence may preclude its translation in the proper reading frame. Comparison of the rabbit class I sequences to those of mouse and human revealed significantly higher homologies between the rabbit and the human than between mouse and rabbit or mouse and human sequences.
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PMID:Rabbit class I MHC genes: cDNA clones define full-length transcripts of an expressed gene and a putative pseudogene. 643 10


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