Mapping the tropomyosin isoform 5 binding site on human erythrocyte tropomodulin: further insights into E-Tmod/TM5 interaction.
Actin protofilaments in the erythrocyte membrane skeleton are uniformly approximately 37nm. This length may be in part attributed to a "molecular ruler" made of erythrocyte tropomodulin (E-Tmod) and tropomyosin (TM) isoforms 5 or 5b. We previously mapped the E-Tmod binding site to TM5 N-terminal heptad repeat residues "a" (I(7), I(14)), "d" (V(10)) and "f" (R(12)). We now map the TM5 binding site to E-Tmod residues at L(116), E(117) and/or E(118) by identifying among 35 deletion clones and a series of point mutations that no longer bind to human TM5 and rat TM5b. Upstream residues 71-104 contain an actin binding site. The N-terminal "KRK ring" may participate in balancing electrostatic force with hydrophobic interaction in dimerization of TM and its binding to E-Tmod.
Vera
Carlos
C
Department of Bioengineering, Jacobs School of Engineering, University of California, San Diego, La Jolla, 92093, USA.
Lao
Jianmin
J
Hamelberg
Donald
D
Sung
Lanping Amy
LA
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D003198:Computer Simulation; D006801:Humans; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D051348:Tropomodulin / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D014335:Tropomyosin / Q000032:analysis / Q000737:chemistry* / Q000235:genetics
C495829:TMOD1 protein, human; C498783:TPM3 protein, human; D051348:Tropomodulin; D014335:Tropomyosin