Protease that enhances BCL10-induced activation: acts via formation of CBM complexes that channel adaptive and innate immune signaling downstream of CARD domain-containing proteins (CARD9, CARD11 and CARD14) to activate NF-kappa-B and MAP kinase p38 pathways which stimulate expression of genes encoding pro-inflammatory cytokines and chemokines (By similarity). Mediates BCL10 cleavage: MALT1-dependent BCL10 cleavage plays an important role in T-cell antigen receptor-induced integrin adhesion (By similarity). Involved in the induction of T helper 17 cells (Th17) differentiation (By similarity). Cleaves RC3H1 and ZC3H12A in response to T-cell receptor (TCR) stimulation which releases their cooperatively repressed targets to promote Th17 cell differentiation (PubMed:25282160). Also mediates cleavage of N4BP1 in T-cells following TCR-mediated activation, leading to N4BP1 inactivation. May also have ubiquitin ligase activity: binds to TRAF6, inducing TRAF6 oligomerization and activation of its ligase activity (By similarity). Homooligomer; forms oligomers which bind to TRAF6. Forms a complex with CARD14 and MALT1; resulting in the formation of a CBM (CARD14-BCL10-MALT1) complex. Forms a complex with CARD11 and MALT1; resulting in the formation of a CBM (CARD11-BCL10-MALT1) complex (By similarity). Forms a complex with CARD9 and MALT1; resulting in the formation of a CBM (CARD9-BCL10-MALT1) complex (PubMed:22265677). Shuttles between the nucleus and cytoplasm. Found in perinuclear structures together with BCL10 (By similarity). Belongs to the peptidase C14B family.