The divergent domains of the NEFA and nucleobindin proteins are derived from an EF-hand ancestor

• Published in: Molecular biology and evolution Vol. 13; no. 7; pp. 990 - 998
• Main Authors: Karabinos, A, Bhattacharya, D, Morys-Wortmann, C, Kroll, K, Hirschfeld, G, Kratzin, H D, Barnikol-Watanabe, S, Hilschmann, N
• Format: Journal Article
• Language: English
• Published: United States 01-09-1996
• Subjects: Amino Acid Sequence; Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Binding Sites; Calcium - metabolism; Calcium-Binding Proteins; Calmodulin - genetics; Calmodulin - metabolism; Cloning, Molecular; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Endonucleases; Evolution, Molecular; Humans; Leucine Zippers; Micrococcal Nuclease; Models, Biological; Models, Genetic; Molecular Sequence Data; Multigene Family; Nerve Tissue Proteins; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Phylogeny; Protein Conformation; Sequence Homology, Amino Acid
• ISSN: 0737-4038; 1537-1719
• DOI: 10.1093/oxfordjournals.molbev.a025667

The human protein NEFA (DNA binding, EF-hand, Acidic region) has previously been isolated from a KM3 cell line and immunolocalized on the plasma membrane, in the cytoplasma, and in the culture medium. Sequence analysis of a cDNA clone encoding NEFA identified a hydrophilic domain, two EF-hands, and a leucine zipper at the C-terminus. These characters are shared with nucleobindin (Nuc). In this paper we have further characterized NEFA and probed its evolutionary origins. Circular dichroism (CD) spectra of recombinant NEFA indicated a helical content of 51% and showed that the EF-hands are capable of binding Ca2+. Experiments with recombinant NEFA and synthesized peptides revealed that the leucine zipper cannot form a homodimer. The leucine zipper may allow heterodimer formation of NEFA and an unknown protein. Phylogenetic analyses suggest that this protein is derived from a four-domain EF-hand ancestor with subsequent duplications and fusions. The leucine zipper and putative DNA-binding domains of NEFA have evolved secondarily from existing EF-hand sequences. These analyses provide insights into how complex proteins may originate and trace the precursor of NEFA to the common ancestor of eukaryotes.