The reference OMIM entry for this protein is 134580

Factor xiii, b subunit; f13b
Fibrin stabilizing factor, b subunit
Fsf, b subunit

DESCRIPTION

The F13B gene encodes the B subunit of factor XIII (EC 2.3.2.13), the last enzyme generated in the blood coagulation cascade. It is the zymogen for fibrinoligase, a transglutaminase that forms intramolecular gamma-glutamyl-epsilon-lysine crosslinking between fibrin molecules and thus stabilizes blood clots. Plasma factor XIII is composed of 2 A subunits (F13A1; 134570), which have catalytic function, and 2 noncatalyic B subunits (F13B), which likely act as carriers proteins. Factor XIII is proteolytically activated by thrombin (F2; 176930) (Takahashi et al., 1986). (An earlier nomenclature for the 2 subunits was A for 'activity' and S for 'support'; B is now substituted for S.)

CLONING

Ichinose et al. (1986) isolated clones corresponding to the beta-subunit of F13 from a human liver cDNA library. The deduced mature 641-residue protein contains 10 repetitive homologous segments, each composed of about 60 amino acids and 4 half-cysteine residues. These repeated segments belong to a family of repeats present in complement factor B (CFB; 138470) and haptoglobin alpha-1 (140100). Three potential Asn-linked carbohydrate attachment sites were also identified in the F13 beta subunit. Grundmann et al. (1990) isolated clones corresponding to the human beta-subunit of factor XIII from a human liver cDNA library, and determined that the deduced 661-residue protein has a molecular mass of 75.5 kD. Nonaka et al. (1993) isolated a full-length cDNA clone of mouse F13b and determined its entire sequence. The predicted amino acid sequence showed 77.5% homology with the human protein.

MAPPING

Leppert et al. (1987) demonstrated linkage of the F13B gene, defined by protein polymorphism, to 2 DNA markers on chromosome 1q: pMLAJ1 and EKH7.4. A VNTR (variable number tandem repeat) polymorphism located about 16 cM distal to Duffy (110700) showed a maximum lod score of 6.00 at theta = 0.217; EKH7.4, a TaqI RFLP located about 20 cM proximal to the REN locus (179820), showed a maximum lod score of 18.69 at theta = 0.088. These results indicated that F13B is located somewhere between 1q12 and 1q32.3, and is more closely situated to the latter band. By in situ hybridization, Webb et al. (1989) assigned F13B to 1q31-q32.1 and perhaps more precisely to subband 1q31.2 or 1q31.3. Rodriguez de Cordoba et al. (1988) found that F13B is closely linked to complement factor H (134370); the maximum lod score was 3.91 at a recombination fraction of 0.0. As pointed out by Hing et al. (1988), the linkage between the factor H and F13B genes (Eiberg et al., 1987) is of interest because of the structural homology between F13B and the RCA (regulator of complement activation) cluster of proteins, to which HF belongs. By in situ hybridization and linkage studies in interspecific backcross mice, Nonaka et al. (1993) mapped the F13B gene to the distal portion of mouse chromosome 1, closely linked to Cfh. Structural similarity between F13b and Cfh, as well as the chromosomal proximity, indicated a close evolutionary relationship of the 2 genes.

MOLECULAR GENETICS

Board (1980) used electrophoresis followed by immunofixation with a specific antiserum to describe genetic variation at the FXIII-beta locus. The locus was shown to be autosomal and to have 3 alleles, with a frequency in Australian blood donors of 0.747, 0.084, and 0.169. Using agarose gel isoelectric focusing followed by immunofixation, Kera et al. (1981) also described pol ... More on the omim web site

Subscribe to this protein entry history

June 30, 2020: Protein entry updated
Automatic update: OMIM entry 134580 was added.

Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).