title: CAP5.5, a life-cycle-regulated, cytoskeleton-associated protein is a member of a novel family of calpain-related proteins in Trypanosoma brucei.
abstract: 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.
authors.affiliation: School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK.
authors.forename: C
authors.initials: C
authors.lastname: Hertz-Fowler
authors.forename: K
authors.initials: K
authors.lastname: Ersfeld
authors.forename: K
authors.initials: K
authors.lastname: Gull
mesh_terms: 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*
chemical_list: D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D015800:Protozoan Proteins; C434320:CAP5.5 protein, Trypanosoma brucei; D002154:Calpain