Catalyzes the cross-linking of proteins and the conjugation of polyamines to proteins. Contributes to the formation of the cornified cell envelope of keratinocytes. L-glutaminyl-[protein] + L-lysyl-[protein] = [protein]-L-lysyl-N(6)-5-L-glutamyl-[protein] + NH4(+) Binds 1 Ca(2+) ion per subunit. Associated with intermediate filaments. Expressed in foreskin keratinocytes. By 12-O-tetradecanoylphorbol-13-acetate (TPA) and calcium in NHEK cells. The disease is caused by variants affecting the gene represented in this entry. Belongs to the transglutaminase superfamily. Transglutaminase family.