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Cartilage Acidic Protein 2 a hyperthermostable, high affinity calcium-binding protein
Liliana Anjos1, Ana S Gomes, Eduardo P Melo
1Comparative and Molecular Endocrinology Group, CCMAR, CIMAR-Laboratório Associado, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. lanjos@ualg.pt
Biochimica Et Biophysica Acta
|January 2, 2013
Summary
Cartilage Acidic Protein 2 (CRTAC2), a novel protein found in teleost fish, binds calcium with high affinity. This protein is hyperthermostable and promotes epithelial cell growth, suggesting functional similarities to mammalian CRTAC1.
Area of Science:
- Biochemistry
- Structural Biology
- Fish Biology
Background:
- Cartilage Acidic Protein 2 (CRTAC2) is a novel protein conserved across species, with high expression in teleost fish pituitary glands.
- CRTAC2 is an isoform of CRTAC1, a human chondrocyte marker, and both are non-integrins with potential Ca(2+)-binding motifs.
Purpose of the Study:
- To elucidate the structure and function of sea bream CRTAC2 (sbCRTAC2).
- To investigate the Ca(2+) binding properties, thermal stability, and potential biological activity of sbCRTAC2.
Main Methods:
- Recombinant sbCRTAC2 expression and structural analysis (α-helix, β-sheet, unordered content).
- Calcium binding assays (affinity, stoichiometry, Gibbs free energy).
- Fluorescence emission spectroscopy to assess thermal stability and chemical denaturation.
Main Results:
- sbCRTAC2 structure: 8.8% α-helix, 33.4% β-sheet, 57.8% unordered.
- High-affinity Ca(2+) binding (K(d)=1.46nM, ∆G=-12.4kcal/mol) with six binding sites per molecule.
- Protein exhibits hyperthermostability (25-95°C) and promotes epithelial cell outgrowth in vitro.
Conclusions:
- sbCRTAC2 possesses high affinity for Ca(2+) and remarkable thermal stability.
- The protein's ability to promote epithelial cell outgrowth suggests functional homology with mammalian CRTAC1 in cell interactions.
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