Mitochondrial ceruloplasmin of mammals

• Published in: Molecular biology (New York) Vol. 39; no. 1; pp. 42 - 52
• Main Authors: Vasin, A. V., Platonova, N. A., Povalihin, R. G., Klotchenko, S. A., Samsonov, S. A., Tsymbalenko, N. V., Puchkova, L. V.
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.01.2005
• Subjects: Binding sites; Genes; Mitochondria; Molecular weight; Polypeptides
• ISSN: 0026-8933; 1608-3245
• DOI: 10.1007/s11008-005-0006-z

Immunoblotting has been used to detect ceruloplasmin (Cp) polypeptides in rat mitochondria isolated from the brain, liver, testes, and mammary glands. It has been found that Cp is contained in the matrix and inner membranes of mitochondria, and that its molecular weight corresponds to the nonglycosylated form of the protein. Computer analysis has not identified sequences encoding the signal peptide for mitochondria protein import (SPMPI) in the chromosomal Cp gene of rats. However, the analysis of Cp-encoding sequences from databases has shown the presence of SPMPI nucleotide sequences in the human processed Cp pseudogene. A 984-nt region of the Cp pseudogene is translated in the only reading frame to yield a polypeptide consisting of 328 amino acid residues (aa) that contains a 66-aa SPMPI at its N-terminus. The predicted protein (without SPMPI) is 92% identical to the corresponding Cp fragment and contains 20 amino acid substitutions, including eight significant substitutions. The His--X--His motif characteristic of copper-containing ferroxidases is in the middle of the molecule. The substitution of proline by histidine at position 923 of Cp results in a potential copper-binding site. The transcription product of the Cp pseudogene has been found in cultured HepG2 and HuTu 80 human cells with the use of RT--PCR. A 30-kDa polypeptide interacting with antibodies to human Cp has been found in the mitochondria of HuTu 80 cells. The possible biological role of mitochondrial Cp is discussed.[PUBLICATION ABSTRACT]