Biochemical Characterisation of Human Transglutaminase 4

Abstract

Transglutaminases are protein-modifying enzymes involved in physiological and pathological processes with potent therapeutic possibilities. Human TG4, also called prostate transglutaminase, is involved in the development of autoimmune and tumour diseases. Although rodent TG4 is well characterised, biochemical characteristics of human TG4 that could help th e understanding of its way of action are not published. First, we analysed proteomics databases and found that TG4 protein is present in human tissues beyond the prostate. Then, we studied in vitro the transamidase activity of human TG4 and its regulation using the microtitre plate method. Human TG4 has low transamidase activity which prefers slightly acidic pH and a reducing environment. It is enhanced by submicellar concentrations of SDS suggesting that membrane proximity is an important regulatory event. Human TG4 does not bind GTP as tested by GTP-agarose and BODIPY-FL-GTPγS binding, and its proteolytic activation by dispase or when expressed in AD-293 cells was not observed either. We identified several potential human TG4 glutamine donor substrates in the AD-293 cell extract by biotin-pentylamine incorporation and mass spectrometry. Several of these potential substrates are involved in cell–cell interaction, adhesion and proliferation, suggesting that human TG4 could become an anticancer therapeutic target.

Transglutaminase 2 is an RNA-binding protein: Experimental verification and characterisation of a novel transglutaminase feature

“…The results were imported into the Scaffold 5.0 program (Proteome Software, Inc., Portland, OR, USA). To prevent the loss of any potential RBPs, non-FDR filtering mode and one unique peptide per protein criterion were used, but the MS/MS spectrum of each peptide was verified by the presence of at least four consequent b or y fragment ions similar to our earlier publication (Csobán-Szabó et al, 2021).…”

The role of transglutaminase 2 in regulation of the balance between autophagy and apoptosis in tumor cells

“…У нокаутных по TGM3 (transglutaminase 3) мышей нарушается формирование волосяного покрова и наблюдается истощение лорикрина -основного компонента клеточной оболочки эпидермальных клеток [9]. Трансглутаминаза 4 участвует в формировании копулятивной пробки у мышей, в то время как повышенная экспрессия TG4 у человека приводит к развитию агрессивного фенотипа рака простаты [10,11]. Трансглутаминаза 6 играет большую роль в возникновении ряда нейродегенеративных заболеваний, включая болезнь Хантингтона [12].…”