title: Homodimerization of calpain 3 penta-EF-hand domain.
abstract: Calpains 1 and 2 are heterodimeric proteases in which large (relative molecular mass M(r) 80000) and small (M(r) 28000) subunits are linked through their respective PEF (penta-EF-hand) domains. The skeletal muscle-specific calpain 3 is believed not to form a heterodimer with the small subunit but might homodimerize through its PEF domain. Size-exclusion chromatography and analytical ultracentrifugation of the recombinant PEF domain of calpain 3 show that it forms a stable homodimer that does not dissociate on dilution. Molecular modelling suggests that there would be no barriers to the dimerization of the whole enzyme through the PEF domains. This orientation would place the catalytic centres at opposite ends of the dimer.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, ON, Canada K7L 3N6.
authors.forename: Ravikiran
authors.initials: R
authors.lastname: Ravulapalli
authors.forename: Beatriz Garcia
authors.initials: BG
authors.lastname: Diaz
authors.forename: Robert L
authors.initials: RL
authors.lastname: Campbell
authors.forename: Peter L
authors.initials: PL
authors.lastname: Davies
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002154:Calpain / Q000737:chemistry*; D019281:Dimerization; D020832:EF Hand Motifs; D004926:Escherichia coli; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology
chemical_list: D002154:Calpain; C078134:calpain p94