RRC ID 49626
Author Homareda H, Otsu M, Yamamoto S, Ushimaru M, Ito S, Fukutomi T, Jo T, Eishi Y, Hara Y.
Title A possible mechanism for low affinity of silkworm Na+/K+-ATPase for K.
Journal J. Bioenerg. Biomembr.
Abstract The affinity for K+ of silkworm nerve Na+/K+-ATPase is markedly lower than that of mammalian Na+/K+-ATPase (Homareda 2010). In order to obtain clues on the molecular basis of the difference in K+ affinities, we cloned cDNAs of silkworm (Bombyx mori) nerve Na+/K+-ATPase α and β subunits, and analyzed the deduced amino acid sequences. The molecular masses of the α and β subunits were presumed to be 111.5 kDa with ten transmembrane segments and 37.7 kDa with a single transmembrane segment, respectively. The α subunit showed 75% identity and 93% homology with the pig Na+/K+-ATPase α1 subunit. On the other hand, the amino acid identity of the β subunit with mammalian counterparts was as low as 30%. Cloned α and β cDNAs were co-expressed in cultured silkworm ovary-derived cells, BM-N cells, which lack endogenous Na+/K+-ATPase. Na+/K+-ATPase expressed in the cultured cells showed a low affinity for K+ and a high affinity for Na+, characteristic of the silkworm nerve Na+/K+-ATPase. These results suggest that the β subunit is responsible for the affinity for K+ of Na+/K+-ATPase.
Volume 49(6)
Pages 463-472
Published 2017-12
DOI 10.1007/s10863-017-9729-5
PII 10.1007/s10863-017-9729-5
PMID 29047027
MeSH Amino Acid Sequence Animals Bombyx / enzymology* DNA, Complementary Potassium / metabolism* Protein Binding Protein Subunits / metabolism Protein Subunits / physiology Sodium-Potassium-Exchanging ATPase / chemistry* Sodium-Potassium-Exchanging ATPase / metabolism
IF 2.914
Resource
Silkworms p20