Expression and cellular localisation of calpain-like proteins in Trypanosoma brucei.
Calpains are a ubiquitous family of calcium-dependent cysteine proteases involved in a wide range of cell regulatory and differentiation processes. In many protozoan organisms, atypical calpains have been discovered that lack the characteristic calcium-binding penta-EF-hand motif of typical vertebrate calpains and most of these novel calpain-like proteins are non-enzymatic homologues of typical calpains. The gene family is particularly expanded in ciliates and kinetoplastids, comprising 25 members in the parasite Trypanosoma brucei. Unique to kinetoplastids, some calpain-like proteins contain N-terminal dual myristoylation/palmitoylation signals, a protein modification involved in protein-membrane associations. We analyzed the expression of calpain-like proteins in the insect (procyclic) and bloodstream-stage of T. brucei using quantitative real time PCR and identified the differential expression of some of the calpain genes. We also present a comprehensive analysis of the subcellular localisation of selected members of this protein family in trypanosomes. Here, of particular interest is the role of protein acylation for targeting to the flagellum. We show that, although acylation is important for flagellar targeting, additional signals are required to specify the precise subcellular localisation.
Liu
Wen
W
Department of Biological Sciences, University of Hull, UK.
Apagyi
Katinka
K
McLeavy
Lorraine
L
Ersfeld
Klaus
K
D002154:Calpain / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D005810:Multigene Family; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
D015800:Protozoan Proteins; D002154:Calpain