CAP5.5, a life-cycle-regulated, cytoskeleton-associated protein is a member of a novel family of calpain-related proteins in Trypanosoma brucei.
The cell shape of African trypanosomes is determined by the presence of an extensive subpellicular microtubule cytoskeleton. Other possible functions of the cytoskeleton, such as providing a potential framework for signalling proteins transducing information from the intracellular and extracellular environment, have not yet been investigated in trypanosomes. In this study, we have identified a novel cytoskeleton-associated protein in Trypanosoma brucei. CAP5.5 is the first member of a new family of proteins in trypanosomes, characterised by their similarity to the catalytic region of calpain-type proteases. CAP5.5 is only expressed in procyclic, but not in bloodstream, trypanosomes. Furthermore, CAP5.5 has been shown to be both myristoylated and palmitoylated, suggesting a stable interaction with the cell membrane. A bioinformatics analysis of the trypanosome genome revealed a diverse family of calpain-related proteins with primary structures similar to CAP5.5, but of varying length. We suggest a nomenclature for this new family of proteins in T. brucei.
Hertz-Fowler
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School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK.
Ersfeld
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Gull
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D000595:Amino Acid Sequence; D000818:Animals; D002154:Calpain / Q000235:genetics*; D002451:Cell Compartmentation; D018797:Cell Cycle Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018503:Genome, Protozoan; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D015800:Protozoan Proteins; D017386:Sequence Homology, Amino Acid; D014346:Trypanosoma brucei brucei / Q000201:enzymology / Q000235:genetics*
D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D015800:Protozoan Proteins; C434320:CAP5.5 protein, Trypanosoma brucei; D002154:Calpain