Tryptase alpha-1 and tryptase beta-1 are enzymes that in humans are encoded by the same TPSAB1gene.[1][2] Beta tryptases appear to be the main isoenzymes expressed in mast cells; whereas in basophils, alpha tryptases predominate.[3]
Function
Tryptases comprise a family of trypsin-like serine proteases, the peptidase family S1. Tryptases are enzymatically active only as heparin-stabilized tetramers, and they are resistant to all known endogenous proteinase inhibitors. Several tryptase genes are clustered on chromosome 16p13.3. These genes are characterized by several distinct features. They have a highly conserved 3' UTR and contain tandem repeat sequences at the 5' flank and 3' UTR which are thought to play a role in regulation of the mRNA stability. These genes have an intron immediately upstream of the initiator Met codon, which separates the site of transcription initiation from protein coding sequence. This feature is characteristic of tryptases but is unusual in other genes. The alleles of this gene exhibit an unusual amount of sequence variation, such that the alleles were once thought to represent two separate genes, alpha and beta 1.Tryptases have been implicated as mediators in the pathogenesis of asthma and other allergic and inflammatory disorders.[3]
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Xia HZ, Kepley CL, Sakai K, et al. (1995). "Quantitation of tryptase, chymase, Fc epsilon RI alpha, and Fc epsilon RI gamma mRNAs in human mast cells and basophils by competitive reverse transcription-polymerase chain reaction". J. Immunol. 154 (10): 5472–80. PMID7730649.
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Xia HZ, Du Z, Craig S, et al. (1997). "Effect of recombinant human IL-4 on tryptase, chymase, and Fc epsilon receptor type I expression in recombinant human stem cell factor-dependent fetal liver-derived human mast cells". J. Immunol. 159 (6): 2911–21. PMID9300715.
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Huang C, Li L, Krilis SA, et al. (1999). "Human tryptases alpha and beta/II are functionally distinct due, in part, to a single amino acid difference in one of the surface loops that forms the substrate-binding cleft". J. Biol. Chem. 274 (28): 19670–6. doi:10.1074/jbc.274.28.19670. PMID10391906.