KOSEN 한인과학기술자네트워크

NCBI에 나온 자료인데 이런 걸 원하시는 것인지요? 도움이 되길 바랍니다. --------------------- Prolyl 4-hydroxylase (EC 1.14.11.2) plays a central role in collagen synthesis. It catalyzes the formation of 4-hydroxyproline in collagens by hydroxylation of proline residues in peptide linkages. The 4-hydroxyproline residues are essential for the folding of the newly synthesized procollagen polypeptide chain into triple helical molecules. The active enzyme is a tetramer of 2 alpha and 2 beta subunits with a molecular weight of about 240,000. The beta subunit (P4HB; 176790) is identical to the enzyme disulfide isomerase (EC 5.3.4.1) and a major cellular thyroid-binding protein. The alpha subunit probably contributes a major part of the catalytic site of the enzyme. Helaakoski et al. (1989) isolated cDNA clones for the alpha subunit. They found that the clones encode a polypeptide of 517 amino acid residues and a signal peptide of 17 amino acids. Southern blot analyses of human genomic DNA with a cDNA probe for the alpha subunit suggested the presence of only 1 gene encoding 2 types of mRNA, which appear to result from mutually exclusive alternative splicing of primary transcripts of 1 gene. Helaakoski et al. (1994) reported that the P4HA gene covers more than 69 kilobases and consists of 16 exons. Evidence had previously been presented for a mutually exclusive alternative splicing of RNA transcripts of the gene. The present data indicated that the mutually exclusive sequences found in the mRNAs are coded by 2 consecutive, homologous 71-bp exons, 9 and 10. These exons are identical in their first 5 basepairs and the overall identity between them is 61% at the nucleotide level and 58% at the level of the coded amino acids. Both types of mRNA were found to be expressed in all of the tissues studied, but in some tissues the type coding for the exon 9 or exon 10 sequences was more abundant than the other type. Helaakoski et al. (1995) and Annunen et al. (1997) demonstrated in the mouse and human, respectively, a second prolyl 4-hydroxylase alpha polypeptide, designated alpha(II); see P4HA2 (600608). Friedman et al. (2000) found that the genome of C. elegans also possesses 2 genes that encode alpha subunits of prolyl 4-hydroxylase. The authors generated deletions within each gene to eliminate enzymatic activity. The deletion in one caused an aberrant body morphology, consistent with a role of prolyl 4-hydroxylase in formation of the body cuticle. The other mutant was phenotypically wildtype. However, the double mutant was not viable, suggesting an essential role for prolyl 4-hydroxylase that is normally accomplished by one gene or the other gene. The effects of the double mutation were mimicked by small-molecule inhibitors of prolyl 4-hydroxylase, validating the genetic results and suggesting that C. elegans can serve as a model system for the discovery of new inhibitors. By Southern blot analysis of rodent-human cell hybrids and by in situ hybridization, Pajunen et al. (1989) mapped the P4HA gene to 10q21.3-q23.1. REFERENCES 1. Annunen, P.; Helaakoski, T.; Myllyharju, J.; Veijola, J.; Pihlajaniemi, T.; Kivirikko, K. I. : Cloning of the human prolyl 4-hydroxylase alpha subunit isoform alpha(II) and characterization of the type II enzyme tetramer: the alpha(I) and alpha(II) subunits do not form a mixed alpha(I)alpha(II)beta2 tetramer. J. Biol. Chem. 272: 17342-17348, 1997. PubMed ID : 9211872 2. Friedman, L.; Higgin, J. J.; Moulder, G.; Barstead, R.; Raines, R. T.; Kimble, J. : Prolyl 4-hydroxylase is required for viability and morphogenesis in Caenorhabditis elegans. Proc. Nat. Acad. Sci. 97: 4736-4741, 2000. PubMed ID : 10781079 3. Helaakoski, T.; Annunen, P.; Vuori, K.; MacNeil, I. A.; Pihlajaniemi, T.; Kivirikko, K. I. : Cloning, baculovirus expression, and characterization of a second mouse prolyl 4-hydroxylase alpha-subunit isoform: formation of an alpha(2)beta(2) tetramer with the protein disulfide-isomerase/beta subunit. Proc. Nat. Acad. Sci. 92: 4427-4431, 1995. PubMed ID : 7753822 4. Helaakoski, T.; Veijola, J.; Vuori, K.; Rehn, M.; Chow, L. T.; Taillon-Miller, P.; Kivirikko, K. I.; Pihlajaniemi, T. : Structure and expression of the human gene for the alpha subunit of prolyl 4-hydroxylase: the two alternatively spliced types of mRNA correspond to two homologous exons the sequences of which are expressed in a variety of tissues. J. Biol. Chem. 269: 27847-27854, 1994. PubMed ID : 7961714 5. Helaakoski, T.; Vuori, K.; Myllyla, R.; Kivirikko, K. I.; Pihlajaniemi, T. : Molecular cloning of the alpha-subunit of human prolyl 4-hydroxylase: the complete cDNA-derived amino acid sequence and evidence for alternative splicing of RNA transcripts. Proc. Nat. Acad. Sci. 86: 4392-4396, 1989. PubMed ID : 2543975 6. Pajunen, L.; Jones, T. A.; Helaakoski, T.; Pihlajaniemi, T.; Solomon, E.; Sheer, D.; Kivirikko, K. I. : Assignment of the gene coding for the alpha-subunit of prolyl 4-hydroxylase to human chromosome region 10q21.3-23.1. Am. J. Hum. Genet. 45: 829-834, 1989. PubMed ID : 2556027