PDBsum entry 2mdf

Proton transport

PDB id: 2mdf

Contents

Protein chain

57 a.a.

PDB id:

2mdf

Name:

Proton transport

Title:

Nmr structure of a two-transmembrane segment tm vi-vii of nhe1

Structure:

Sodium/hydrogen exchanger 1. Chain: a. Synonym: apnh, na(+)/h(+) antiporter, amiloride-sensitive, na(+)/h(+) exchanger 1, nhe-1, solute carrier family 9 member 1. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: slc9a1, apnh1, nhe1. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

25 models

Authors:

B.L.Lee,B.D.Sykes,C.Alves,L.Fliegel

Key ref:

C.Alves et al. (2014). Structural and functional analysis of the transmembrane segment pair VI and VII of the NHE1 isoform of the Na+/H+ exchanger. Biochemistry, 53, 3658-3670. PubMed id: 24840010 DOI: 10.1021/bi500392y

Date:

10-Sep-13 Release date: 02-Jul-14

Protein chain

P19634  (SL9A1_HUMAN) -  Sodium/hydrogen exchanger 1 from Homo sapiens

Seq: 815 a.a.

Struc: 57 a.a.*

* PDB and UniProt seqs differ at 8 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi500392y

Biochemistry 53:3658-3670 (2014)

PubMed id: 24840010

Structural and functional analysis of the transmembrane segment pair VI and VII of the NHE1 isoform of the Na+/H+ exchanger.

C.Alves, B.L.Lee, B.D.Sykes, L.Fliegel.

ABSTRACT

Isoform 1 of the mammalian Na(+)/H(+) exchanger (NHE1) is a ubiquitously expressed plasma membrane pH regulatory protein. It removes one intracellular H(+) in exchange for one extracellular Na(+). The 500 N-terminal amino acids comprise the catalytic membrane domain and fold into 12 transmembrane (TM) segments. To gain insight into the structure and function of human NHE1, a region spanning transmembrane domains VI and VII was expressed and purified, and the structure was determined using nuclear magnetic resonance (NMR). Segment VI includes two structurally conserved regions corresponding to two short α-helices involving residues 229-236 and 239-247. Segment VII includes one long helical region spanning residues 255-274. The NMR structure of the peptide containing transmembrane domains VI and VII was very similar to the previously published structures of the single-transmembrane segments except that TM VII was not kinked. Tryptophan scanning site-directed mutagenesis of TM VI demonstrated that mutation of residues V240-V245 to tryptophan eliminated NHE1 activity when the full length protein was expressed in cells. In contrast, mutants F246W and E247W were functional. Double mutant V242F/F260V retained activity, while the individual mutations were not active. The results suggest that the region of TM VI from V240 to V245 is closely associated with TM VII and that, in agreement with the NMR structure of VI-VII segments, V242 and F260 are in close association. A study of two transmembrane peptides provides further insight into the structure of the NHE1 protein.