Intracellular targeting of isoproteins in muscle cytoarchitecture.
Part of the muscle creatine kinase (MM-CK) in skeletal muscle of chicken is localized in the M-band of myofibrils, while chicken heart cells containing myofibrils and BB-CK, but not expressing MM-CK, do not show this association. The specificity of the MM-CK interaction was tested using cultured chicken heart cells as "living test tubes" by microinjection of in vitro generated MM-CK and hybrid M-CK/B-CK mRNA with SP6 RNA polymerase. The resulting translation products were detected in injected cells with isoprotein-specific antibodies. M-CK molecules and translation products of chimeric cDNA molecules containing the head half of the B-CK and the tail half of the M-CK coding regions were localized in the M-band of the myofibrils. The tail, but not the head portion of M-CK is essential for the association of M-CK with the M-band of myofibrils. We conclude that gross biochemical properties do not always coincide with a molecule's specific functions like the participation in cell cytoarchitecture which may depend on molecular targeting even within the same cellular compartment.
Schäfer
B W
BW
Institute for Cell Biology, Swiss Federal Institute of Technology, Zurich.
Perriard
J C
JC
D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D064211:Connectin; D003402:Creatine Kinase / Q000032:analysis* / Q000235:genetics; D005455:Fluorescent Antibody Technique; D007527:Isoenzymes / Q000032:analysis*; D008845:Microinjections; D009124:Muscle Proteins / Q000032:analysis; D009206:Myocardium / Q000201:enzymology*; D009210:Myofibrils / Q000201:enzymology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics
D064211:Connectin; D007527:Isoenzymes; D009124:Muscle Proteins; D012333:RNA, Messenger; D003402:Creatine Kinase