Different Ca2+-sensitivities between the EF-hands of T- and L-plastins

Plastins are Ca2+-regulated actin-bundling proteins, and essential for developing and stabilizing actin cytoskeletons. T-plastin is expressed in epithelial and mesenchymal cells of solid tissues, whereas L-plastin is expressed in mobile cells such as hemopoietic cell lineages and cancer cells.Using various spectroscopic methods, gel-filtration chromatography, and isothermal titration calorimetry, we here demonstrate that the EF-hand motifs of both T- and L-plastin change their structures in response to Ca2+, but the sensitivity to Ca2+ is lower in T-plastin than in L-plastin. These results suggest that T-plastin is suitable for maintaining static cytoskeletons, whereas L-plastin is suitable for dynamic rearrangement of cytoskeletons.

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► Ca2+-regulated secondary structure change of the EF-hands of T-plastin (EFT) is small.
► That of the EF-hands of L-plastin (EFL) is large.
► Change in the tertiary structure of both EFT and EFL is large.
► Ca2+ sensitivity and affinity is lower in EFT than in EFL.