Cation‐ and peptide‐binding properties of human centrin 2

[摘要]

Centrin and calmodulin (CaM) are closely related four-EF-hand Ca²⁺-binding proteins. While CaM is monomeric, centrin 2 is dimeric and binds only two Ca²⁺ per dimer, likely to site IV in each monomer. Ca²⁺ binding to centrin 2 displays pronounced negative cooperativity and a [Ca²⁺]_0.5 of 30 μM. As in CaM, Ca²⁺ binding leads to the exposure of a hydrophobic probe-accessible patch on the surface of centrin 2. Provided Ca²⁺ is present, centrin 2 forms a 1:1 peptide:monomer complex with melittin with an affinity of 100 nM. The complex binds four instead of two Ca²⁺. Our data point to surprising differences in the mode of activation of these homologous proteins.

[学科分类] 生物化学/生物物理

[关键词] Centrosome;Ca2+-binding protein;EF-hand motif;Conformational change;Protein–peptide interaction;CaM;calmodulin;ME;melittin;[Ca2+]0.5;calcium concentration at half-maximal change;K Ca;stoichiometric Ca2+-binding constant;TNS;2-p-toluidinylnaphthalene-6-sulfonate;ANS;8-anilino-1-naphthalenesulfonate