The calpain 1-alpha-actinin interaction. Resting complex between the calcium-dependent protease and its target in cytoskeleton.
Calpain 1 behaviour toward cytoskeletal targets was investigated using two alpha-actinin isoforms from smooth and skeletal muscles. These two isoforms which are, respectively, sensitive and resistant to calpain cleavage, interact with the protease when using in vitro binding assays. The stability of the complexes in EGTA [Kd(-Ca2+) = 0.5 +/- 0.1 microM] was improved in the presence of 1 mm calcium ions [Kd(+Ca2+) = 0.05 +/- 0.01 microM]. Location of the binding structures shows that the C-terminal domain of alpha-actinin and each calpain subunit, 28 and 80 kDa, participates in the interaction. In particular, the autolysed calpain form (76/18) affords a similar binding compared to the 80/28 intact enzyme, with an identified binding site in the catalytic subunit, located in the C-terminal region of the chain (domain III-IV). The in vivo colocalization of calpain 1 and alpha-actinin was shown to be likely in the presence of calcium, when permeabilized muscle fibres were supplemented by exogenous calpain 1 and the presence of calpain 1 in Z-line cores was shown by gold-labelled antibodies. The demonstration of such a colocalization was brought by coimmunoprecipitation experiments of calpain 1 and alpha-actinin from C2.7 myogenic cells. We propose that calpain 1 interacts in a resting state with cytoskeletal targets, and that this binding is strengthened in pathological conditions, such as ischaemia and dystrophies, associated with high calcium concentrations.
Raynaud
Fabrice
F
UMR 5539 - CNRS, laboratoire de Motilité Cellulaire - EPHE, cc107, USTL, Montpellier, France.
Bonnal
Chantal
C
Fernandez
Eric
E
Bremaud
Laure
L
Cerutti
Martine
M
Lebart
Marie-Christine
MC
Roustan
Claude
C
Ouali
Ahmed
A
Benyamin
Yves
Y
D000185:Actinin / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002154:Calpain / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism
D021122:Protein Subunits; D000185:Actinin; D002154:Calpain; D002118:Calcium