Nucleobindin-1 (NUCB1), also known as calnuc, is a protein that in humans is encoded by the NUCB1 gene. Structure The human calnuc protein contains 461 amino acids and has a pI of 4.9. The protein contains the following regions and domains: Signal peptide Leucine-zipper The leucine-zipper of calnuc may be responsible for its dimerization. aa 347-389 – Nuclear localization signal 2 zinc binding sites with high affinity (Kd = 20 nM) carboxypeptidase-like motifs : HFREXnH (aa 66) and HFTEXnH (aa 146) 2 EF-hands Potential anchor region– 15-aa hydrophobic region at its COOH terminus that may be sufficient for membrane anchoring References Further reading EF-hand-containing proteins