Mm. Exner et al., ISOLATION AND CHARACTERIZATION OF A FAMILY OF PORIN PROTEINS FROM HELICOBACTER-PYLORI, Infection and immunity, 63(4), 1995, pp. 1567-1572
Two-dimensional gel electrophoresis was used to identify heat-modifiab
le outer membrane proteins, which were candidates for porins, from Hel
icobacter pylori membrane preparations, Four such proteins with appare
nt molecular masses of 48, 49, 50, and 67 kDa were isolated. The four
proteins copurified together after selective detergent solubilizations
followed by anion-exchange chromatography, and each protein was ultim
ately purified to homogeneity by gel purification, These proteins were
then tested for pore-forming ability with a planar lipid bilayer mode
l membrane system. All four proteins appeared to be present as monomer
s, and they formed pores with low single-channel conductances in 1.0 M
KCl of 0.36, 0.36, 0.30, and 0.25 nS, respectively, for the 48-, 49-,
50, and 67-kDa proteins which we propose to designate HopA, HopB, Hop
C, and HopD, N-terminal amino acid sequence analyses showed a high deg
ree of homology among all four proteins, and it appears that these pro
teins constitute a family of related porins in H. pylori.