Characterization of components of Z-bands in the fibrillar flight muscle of Drosophila melanogaster.
Twelve monoclonal antibodies have been raised against proteins in preparations of Z-disks isolated from Drosophila melanogaster flight muscle. The monoclonal antibodies that recognized Z-band components were identified by immunofluorescence microscopy of flight muscle myofibrils. These antibodies have identified three Z-disk antigens on immunoblots of myofibrillar proteins. Monoclonal antibodies alpha:1-4 recognize a 90-100-kD protein which we identify as alpha-actinin on the basis of cross-reactivity with antibodies raised against honeybee and vertebrate alpha-actinins. Monoclonal antibodies P:1-4 bind to the high molecular mass protein, projectin, a component of connecting filaments that link the ends of thick filaments to the Z-band in insect asynchronous flight muscles. The anti-projectin antibodies also stain synchronous muscle, but, surprisingly, the epitopes here are within the A-bands, not between the A- and Z-bands, as in flight muscle. Monoclonal antibodies Z(210):1-4 recognize a 210-kD protein that has not been previously shown to be a Z-band structural component. A fourth antigen, resolved as a doublet (approximately 400/600 kD) on immunoblots of Drosophila fibrillar proteins, is detected by a cross reacting antibody, Z(400):2, raised against a protein in isolated honeybee Z-disks. On Lowicryl sections of asynchronous flight muscle, indirect immunogold staining has localized alpha-actinin and the 210-kD protein throughout the matrix of the Z-band, projectin between the Z- and A-bands, and the 400/600-kD components at the I-band/Z-band junction. Drosophila alpha-actinin, projectin, and the 400/600-kD components share some antigenic determinants with corresponding honeybee proteins, but no honeybee protein interacts with any of the Z(210) antibodies.
Saide
J D
JD
Department of Physiology, Boston University School of Medicine, Massachusetts 02118.
Chin-Bow
S
S
Hogan-Sheldon
J
J
Busquets-Turner
L
L
Vigoreaux
J O
JO
Valgeirsdottir
K
K
Pardue
M L
ML
D000185:Actinin / Q000032:analysis / Q000235:genetics; D000818:Animals; D000911:Antibodies, Monoclonal; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004331:Drosophila melanogaster; D004591:Electrophoresis, Polyacrylamide Gel; D005426:Flight, Animal; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000032:analysis*; D009132:Muscles / Q000032:analysis / Q000648:ultrastructure*; D009210:Myofibrils / Q000032:analysis / Q000648:ultrastructure*
D000911:Antibodies, Monoclonal; D009124:Muscle Proteins; D000185:Actinin; D004247:DNA