- Peptide (C)GDDYHTWNVNYKK, corresponding to amino acid residues 32-44 of mouse HVCN1 (Accession Q3U2S8). Intracellular, N-terminus.
- Mouse WEHI B-cell lymphoma; human HL-60 promyelocytic leukemia and human THP-1 acute monocytic leukemia cell lysates (1:200).
- Western blot analysis of mouse WEHI B-cell lymphoma (lanes 1 and 4), human HL-60 promyelocytic leukemia (lanes 2 and 5) and human THP-1 acute monocytic leukemia (lanes 3 and 6) cell lysates:1-3. Anti-HVCN1 Antibody (#AHC-001), (1:200).
4-6. Anti-HVCN1 Antibody, preincubated with HVCN1 Blocking Peptide (#BLP-HC001).
- 2-5 µg antibody/1x106 fixed and permeabilized human HL-60 promyelocytic leukemia cells.
- The control antigen is not suitable for this application.
Currents measured from voltage-gated proton channels were detected1 long before the channel (HVCN1, also known as HV1 and VSOP) was cloned2,3. HVCN1 has four membrane spanning domains and intracellular N- and C-termini. Interestingly, unlike its voltage-gated ion channel counterparts, HVCN1 has no pore4. Also, functional HVCN1 channels are formed by dimers where each monomer has its own conducting pore, each with its own voltage sensor (voltage sensing occurs similarly to other voltage-gated ion channels)5-8.
The fundamental role of HVCN1 is to pump out protons, thereby increasing the intracellular pH. The channel is exclusively selective for H+ and opens upon membrane depolarization, although its open state hugely depends on the pH on both sides of the membrane4. Its role is best described in leukocytes where phosphorylation via PKC on a Thr residue potentiates the activity of the channel and increases its open state, thereby increasing the H+ current across the membrane, in this manner mediating optimal NADPH-oxidase (whose optimal activity is at pH 7.5) required for the production of reactive oxygen species (ROS) necessary for phagocytosis to occur4.
Apart from leukocytes, HVCN1 is also expressed in basophils where its activation mediates histamine release4,9. In B cells, it maintains optimal signaling, such that ROS production is maintained high10. HVCN1 was found to regulate human spermatozoa activation. Finally, in the airway mucosa, where it regulates pH, channel gating there, is mostly mediated by differences in pH across the membrane as opposed to the membrane potential4.