V-type proton ATPase 116 kDa subunit a isoform 3 (TCIRG1) (TCIRG1)

V-type proton ATPase 116 kDa subunit a isoform 3 (TCIRG1), also known as T-cell immune regulator 1, is a multi-pass membrane protein that functions as the a3 subunit of the V0 domain within the vacuolar-type H+-ATPase (V-ATPase) complex [UniProt Q13488]. It is highly expressed in osteoclasts, where it is indispensable for the acidification of the resorption lacuna, allowing for the dissolution of bone mineral during remodeling [Nature Genetics 25.3 (2000): 343-346]. TCIRG1 also plays a significant role in the immune system, specifically in T-cell activation and the regulation of intracellular pH in various organelles [Gene 220.1-2 (1998): 41-49]. Mutations in the TCIRG1 gene are responsible for approximately 50% of cases of infantile malignant osteopetrosis, a severe genetic disorder characterized by abnormally dense bone and bone marrow failure [UniProt Q13488, Nature Genetics 25.3 (2000): 343-346]. In the context of oncology, TCIRG1 is frequently overexpressed in various cancers, where it facilitates extracellular acidification, promoting protease activity and tumor cell invasion [Journal of Biological Chemistry 284.23 (2009): 15490-15500]. Although it represents a potential therapeutic target for metabolic bone diseases and metastatic cancer, the high conservation of V-ATPase subunits across tissues presents significant challenges for achieving isoform-specific inhibition and avoiding systemic toxicity [PNAS 85.21 (1988): 7972-7976, British Journal of Pharmacology 151.3 (2007): 323-333].

Other names

T-cell immune regulator 1TIRC7OC116a3Vph1OPTB1Atp6iV-type proton ATPase 116 kDa subunit a isoform 3

Inhibition of the V0 domain of the V-type ATPase complex, thereby blocking proton translocation across the plasma membrane or organelle membranes.