Record Details

Dipole moment analysis of membrane proteins suggests role in orientation in the membrane

NOPR - NISCAIR Online Periodicals Repository

View Archive Info
 
 
Field Value
 
Title Dipole moment analysis of membrane proteins suggests role in orientation in the membrane
 
Creator Vasanthi, G
Krishnaswamy, S
 
Description 93-100
The position independent dipole membrane
proteins need to be oriented in the membrane in order to function as channels, transporters
or recognition systems. Membrane proteins can be broadly classified as either predominantly
alpha helical or beta barrel in nature. All the different types of thirteen
beta barrel membrane proteins (2OMF, 2POR, 1 PRN,1PHO,1IIV, lAF6, lAOT, 2MPR,
lOSM, lQJ8, 1BXW, 2FCP and IFEP) and six alpha helical membrane proteins (lBL8,
1MSL, lQLB, lARl, 1PSS and 1QHJ) from the Protein Data Bank were analyzed. Dipole
moment was calculated for both classes of proteins. In all the oligomers, the
orientation of the dipole was found to be parallel to direction of insertion
that is perpendicular to the possible membrane layer. Monomers do not show a similar
orientation. In all the alpha helical oligomers, the dipole points from the
intra-cellular to the extra-cellular side. In the oligomeric beta barrel
proteins, the direction of the dipole is from the extra-cellular to the
intra-cellular side, except for OmpF from E.coli, Omp36 from Klebsiella
pneumonia and LamB from E.coli where the situation is reversed.
However, the dipole moments of the monomeric proteins and the monomers of the
oligomers themselves are not oriented parallel to the molecular axis and the insertion
orientation, but they are almost parallel to the membrane surface. It is
possible that the quaternary oligomeric association is necessary for the
correct orientation in the membrane and this is aided by the dipole
orientation. The electrostatic potential surface calculated with all atoms,
which also do not show clear separation of charge surfaces. Calculations suggest
that backbone structure and oligomer are sufficient for providing the dipole
orientation.
 
Date 2013-07-15T06:58:58Z
2013-07-15T06:58:58Z
2002-04
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/19757
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.39(2) [April 2002]