A SEGMENT CORRESPONDING TO AMINO-ACIDS GLN199-LYS208 OF MURINE IL-1-ALPHA CROSS-REACTS WITH AN ANTIGENIC DETERMINANT LOCALIZED IN THE Z-LINE OF DROSOPHILA-MELANOGASTER MYOFIBRILS

Immunofluorescence microscopic observations indicated that a monoclona l antibody, Vmp 18, raised against the peptide 199-208 of murine inter leukin 1 alpha, cross-reacted with an antigenic determinant of Drosoph ila thorax muscles. Immunoelectron microscopic analysis showed that th e gold particles were mainly localized in the Z-line which is the atta chment site of thin filaments from adjacent sarcomeres. On the contrar y, the antibody failed to mark the Z-line in vertebrate skeletal muscl e. A Western blot of total pro tein extract from Drosophila thorax mus cles bound a protein of 43 kDa. Our observations suggest that the Vmp 18 antibody could contribute to clarify the composition of the Z-line in insect's flight muscles.