M. Asahi et al., Phospholamban domain IB forms an interaction site with the loop between transmembrane helices M6 and M7 of sarco(endo)plasmic reticulum Ca2+ ATPases, P NAS US, 98(18), 2001, pp. 10061-10066
Citations number
29
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Transmembrane helix M6 of the sarco(endo)plasmic reticulum Call ATPase (SER
CA) has been shown to form a site of interaction with phospholamban (PLN).
Site-directed mutagenesis was carried out in the cytoplasmic loop (L67) bet
ween M6 and M7 in SERCA1a to detect other SERCA-PLN binding sites. Mutants
N810A, D813A, and R822A had diminished ability to interact functionally wit
h Pill but only D813A and R822A had reduced physical interaction with PLN.
PLN mutants R25A, Q26A, N27A, L28A, Q29A, and N30A had enhanced physical in
teraction with wild-type (wt) SERCA1a, but physical interaction of these PL
N mutants with SERCA1a mutants D813A and R822A was reduced about 2.5 fold (
range 1.44-2.82). Exceptions were the interactions of PLN N27A and N30A wit
h SERCA1a D813A, which were reduced by 7.3- and 5.8-fold, respectively. A s
uperinhibitory PLN deletion mutant, PLN Delta 21-29, had strong physical in
teractions with SERCA1a and with SERCA1a mutant D813A. Physical interaction
s with SERCA1a and mutant D813A were sharply diminished, however, for the P
LN deletion mutant, PLN Delta 21-30, lacking PLN N30. Physical interactions
between SERCA1a and a PLN-cytochrome b(5) chimera containing PLN residues
1-29 were much stronger than those between a PLN-cytochrome bs chimera cont
aining PLN residues 1-21 and lacking N27. These results suggest that a SERC
A1-PLN interaction site occurs between L67 of SERCA1a and domain IB of PLN,
which involves SERCA1a D813 and PLN N27 and N30.