title: Molecular and genetic mechanisms of factor XIII A subunit deficiency.
abstract: Factor XIII is a proenzyme for a plasma transglutaminase. Factor XIII in plasma is a tetramer (A2B2) held together by noncovalent bonds, and the A subunit contains the active site. Recently, the three-dimensional structure of the A subunit has been determined by x-ray crystallography. To understand the structure-function relationships of the factor XIII molecule and its clinical implications in factor XIII deficiency, we characterized its genetic defects and closely examined its gene products, including mRNA and protein levels. A variety of missense and nonsense mutations (Arg260-Cys, Tyr283-Cys, Gly562-Arg) and deletions/insertions with or without out-of-frame shift/premature termination and splicing abnormalities (4-bp deletion with 464Stop, T insertion at the exon IV/intron D boundary with exon IV-skipping, 20-bp deletion at the exon I/intron A boundary) has been identified in cases demonstrating A subunit deficiency. In some cases, the A subunit mRNA levels were severely reduced. Their molecular and cellular bases have also been explored by expression experiments in mammalian cells and by molecular modeling. In most cases, impaired folding and/or conformational changes of the mutant A subunits lead to both intra- and extracellular instability, which is responsible for the A subunit deficiency in the patients.
authors.affiliation: Department of Molecular Patho-Biochemistry and Patho-Biology, Yamagata University School of Medicine, Japan. aichinos@med.id.yamagata-u.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Ichinose
authors.forename: M
authors.initials: M
authors.lastname: Souri
authors.forename: T
authors.initials: T
authors.lastname: Izumi
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics; D004252:DNA Mutational Analysis; D004789:Enzyme Activation; D005177:Factor XIII Deficiency / Q000235:genetics* / Q000378:metabolism; D005337:Fibrin / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017354:Point Mutation; D011487:Protein Conformation; D012333:RNA, Messenger / Q000096:biosynthesis; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000378:metabolism; D011503:Transglutaminases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D000979:alpha-2-Antiplasmin / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D000979:alpha-2-Antiplasmin; D005337:Fibrin; D011503:Transglutaminases; D013917:Thrombin