Ion selectivity (with preference for cations over anions) of MscMJ and MscMJLR (types of mechano-sensitive channels) and their conductance

Range PK/PCl (both channels) ~5.0: MscMJ conductance 0.3nanosiemens: MscMJLR conductance 2.0nanosiemens
Organism Archaea Methanocaldococcus jannaschii
Reference Martinac B, Saimi Y, Kung C. Ion channels in microbes. Physiol Rev. 2008 Oct88(4):1449-90. doi: 10.1152/physrev.00005.2008. p.1456 left column 3rd paragraphPubMed ID18923187
Primary Source [165] Kloda A, Martinac B. Structural and functional differences between two homologous mechanosensitive channels of Methanococcus jannaschii. EMBO J. 2001 20: 1888–1896.PubMed ID11296222
Method Primary source abstract:"MscMJLR is structurally very similar to MscMJ, the MS channel of M.jannaschii that was identified and cloned first by using the TM1 domain of Escherichia coli MscL as a genetic probe."
Comments P.1456 left column 3rd paragraph:"MscMJ and MscMJLR are the two types of MS channels found in M. jannashii (ref 164, primary source 165). These two channels differ functionally from each other despite sharing 44% sequence identity (ref 240). Although they have similar ion selectivity with preference for cations over anions (PK/PCl ~ 5.0) the conductance of MscMJ of 0.3 nS is much smaller compared to 2.0 nS conductance of MscMJLR (primary source 165). Both channels were identified during inspection of the M. jannashii genome database using the DNA corresponding to the TM1 helix of MscL as a probe. MscMJ comprises 350 residues whereas MscMJLR is a slightly bigger protein comprising 361 residues (primary source 165). Both channels are members of the MscS subfamily of MS channels with both proteins exhibiting approximately 28% sequence identity with overlapping residues of the MscS sequence (ref 163, primary source 165) (Fig. 4)." P stands for (relative) permeabilty
Entered by Uri M
ID 112281