Identification of a new EF-hand superfamily member from Trypanosoma brucei.
We identified several open reading frames between the regions encoding calmodulin and ubiquitin-EP52/1 in the genome of Trypanosoma brucei. One of these, EFH5, encodes a protein 192 amino acids long. The EFH5 transcript is present in poly(A)+ mRNA and is present at similar levels in the mammalian bloodstream form and the insect procyclic form. EFH5 contains four EF-hand homolog domains, two of which are inferred to bind Ca2+ ions. We expressed EFH5 as a fusion protein in Escherichia coli and demonstrated calcium-binding activity of the fusion protein using the 45Ca-overlay technique. The function of EFH5 remains unknown; however, as the fourth EF-hand homolog identified in trypanosomes, it attests to the broad range of functions assumed by calcium functioning as a second messenger. EFH5, which is most closely related to LAV1-2 from Physarum, represents a distinct subfamily among the EF-hand-containing proteins.
Wong
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Department of Microbiology and Immunology, University of California, Los Angeles 90024.
Kretsinger
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Campbell
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D016054:DNA, Protozoan / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D015800:Protozoan Proteins / Q000235:genetics*; D016053:RNA, Protozoan / Q000235:genetics; D016415:Sequence Alignment; D014346:Trypanosoma brucei brucei / Q000235:genetics*
D002135:Calcium-Binding Proteins; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D016053:RNA, Protozoan; C075025:EFH5 protein, Trypanosoma brucei; D002118:Calcium