Identification of calpain cleavage sites in the G1 cyclin-dependent kinase inhibitor p19(INK4d).
Calpains are a large family of Ca2+-dependent cysteine proteases that are ubiquitously distributed across most cell types and vertebrate species. Calpains play a role in cell differentiation, apoptosis, cytoskeletal remodeling, signal transduction and the cell cycle. The cell cycle proteins cyclin D1 and p21(KIP1), for example, have been shown to be affected by calpains. However, the rules that govern calpain cleavage specificity are poorly understood. We report here studies on the pattern of mu-calpain proteolysis of the p19(INK4d) protein, a cyclin-dependent kinase 4/6 inhibitor that negatively regulates the mammalian cell cycle. Our data show new characteristics of calpain action: mu-calpain cleaves p19(INK4d) immediately after the first and second ankyrin repeats that are structurally less stable compared to the other repeats. This is in contrast to features observed so far in the specificity of calpains for their substrates. These results imply that calpain may be involved in the cell cycle by regulating the cell cycle regulatory protein turnover through CDK inhibitors and cyclins.
Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany.
Joma
J
Joy
Narasimharao
N
Nalabothula
Madhumita
M
Ghosh
Oliver
O
Popp
Marianne
M
Jochum
Werner
W
Machleidt
Shirley
S
Gil-Parrado
Tad A
TA
Holak
D017209:Apoptosis / Q000502:physiology; D002154:Calpain / Q000737:chemistry / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D019938:Cyclin D1 / Q000378:metabolism; D050764:Cyclin-Dependent Kinase Inhibitor p19 / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D016193:G1 Phase; D006801:Humans; D015398:Signal Transduction / Q000502:physiology
D018797:Cell Cycle Proteins; D050764:Cyclin-Dependent Kinase Inhibitor p19; D050759:Cyclin-Dependent Kinase Inhibitor p21; D019938:Cyclin D1; D002154:Calpain; C449002:mu-calpain