Structural characterization of calcineurin B homologous protein 1.
Calcineurin B homologous protein 1 (CHP1), also known as p22, is a calcium-binding EF-hand protein that plays a role in membrane trafficking. It binds to multiple effector proteins, including Na(+)/H(+) exchangers, a serine/threonine kinase, and calcineurin, potentially modulating their function. The crystal structure of calcium-bound CHP1 from rat has been determined at 2.2 Angstroms of resolution. The molecule has a compact alpha-helical structure containing four EF-hands. The overall folding topology of the protein is similar to that of the regulatory B subunit of calcineurin and to that of calcium- and integrin-binding protein. The calcium ion is coordinated in typical fashion in the third and fourth EF-hands, but the first and second EF-hands contain no calcium ion. The first EF-hand is maintained by internal interactions, and the second EF-hand is stabilized by hydrophobic interactions. CHP1 contains a hydrophobic pocket on the opposite side of the protein to the EF-hands that has been implicated in ligand binding.
International Graduate School of Arts and Sciences, Yokohama City University, Tsurumi-ku, Japan.
Youichi
Y
Naoe
Kyouhei
K
Arita
Hiroshi
H
Hashimoto
Hiroshi
H
Kanazawa
Mamoru
M
Sato
Toshiyuki
T
Shimizu
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019703:Calcineurin / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000378:metabolism; D007477:Ions; D008024:Ligands; D008074:Lipoproteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014461:Ultracentrifugation
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D007477:Ions; D008024:Ligands; D008074:Lipoproteins; D010455:Peptides; C098929:calcium binding protein p22, rat; D019703:Calcineurin; D002118:Calcium