Tryptase is the major neutral protease present in mast cells and is secreted upon the coupled activation-degranulation response of this cell type. May play a role in innate immunity (By similarity). Preferential cleavage: Arg-|-Xaa, Lys-|-Xaa, but with more restricted specificity than trypsin. The alternative splicing event is due to a G to A point mutation at the exon 2/intron 2 splice site and causes loss of protein expression. The alternatively spliced transcript is only found in C57BL/6 mouse. Is not expressed in mature serosal or mucosal mast cells and is expressed only transiently at an early stage of in vitro mast cell differentiation. Belongs to the peptidase S1 family. Tryptase subfamily.