Proton channels in molluscs: A new bivalvian-specific minimal H 4 channel.

Recently, three proton channels (H ) have been identified and characterized in Aplysia californica (AcH 1-3). Focusing on AcH 1 and AcH 2, analysis of Transcriptome Shotgun Assembly and genomic databases of 91 molluscs identified H homologous channels in other molluscs: channels homologous to AcH 1 and to AcH 2 were found in 90 species (56 full-length sequences) and in 33 species (18 full-length sequences), respectively. Here, we report the discovery of a fourth distinct proton channel family, H 4.

Unexpected expansion of the voltage-gated proton channel family.

Voltage-gated ion channels, whose first identified function was to generate action potentials, are divided into subfamilies with numerous members. The family of voltage-gated proton channels (H ) is tiny. To date, all species found to express H have exclusively one gene that codes for this unique ion channel.

Zinc modulation of proton currents in a new voltage-gated proton channel suggests a mechanism of inhibition.

The H 1 voltage-gated proton (H 1) channel is a key component of the cellular proton extrusion machinery and is pivotal for charge compensation during the respiratory burst of phagocytes. The best-described physiological inhibitor of H 1 is Zn . Externally applied ZnCl drastically reduces proton currents reportedly recorded in Homo sapiens, Rattus norvegicus, Mus musculus, Oryctolagus cuniculus, Rana esculenta, Helix aspersa, Ciona intestinalis, Coccolithus pelagicus, Emiliania huxleyi, Danio rerio, Helisoma trivolvis, and Lingulodinium polyedrum, but with considerable species variability.

Antibody-mediated sialidase activity in blood serum of patients with multiple myeloma.

Cell surface sialylation is known to be tightly connected with tumorigenicity, invasiveness, metastatic potential, clearance of aged cells, while the sialylation of IgG molecules determines their anti-inflammatory properties. Four sialidases - hydrolytic enzymes responsible for cleavage of sialic residues - were described in different cellular compartments. However, sialidases activity in body fluids, and specifically in blood serum, remains poorly studied.