Ultrastractural localization of dystrophin N-terminal dinding proteins and their relation to dystrophin in normal skeletal myofiber.

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Calmodulin, aciculin and talin are known to link dystrophin diochemically. Among them calmodulin is reported to bind bystrophin at N terminal doma-in and the binding sites of other two proteins, aciculin and talin, are unknown. This investigation is undertaken to demonstrate that calmodulin, aciculin and talin associate with dystrophin, and further to detect the linking point at ultrastructural level. The rabbit antibodies against sy-nthetic peptide of 12 amino acid residues of aciculin peptide D (Belkin AM et al. J Cell Sci 107 : 159-173,1994) and against purified bovine brain calmodulin are generated. The monoclonal antibody against talin was avai-lable in commercial base. Double immunoglold labeling electron microscopy with (1) rabbit antiaciculin and sheep antidystrophin antibodies, and rab-bit antiaciculin and sheep antispectrin antibodies (2) monoclonal antita-lin and sheep antidystrophin antibodies, and monoclonal antitalin and sheep antispectrin antibodies (3) rabbit anticalmodulin and sheep antidystrophin antibodies and rabbit anticalmodulin and sheep antispectrin antibodies using histochemically normal human muscle disclosed that the epitopes of aciculin, talin and calmodulin formed more frequently doublet with dystrophin epitope than with spectrin epitope. Single blind analysis of doublet formation in the antibody combination of aciculin and dystrophin, and aciculin and spectrin showed that the doublet percents were 23.5(]SY.+-。[)1.8 (SE) and 12.8(]SY.+-。[)1.1 (P<0.01), respectively. In the analysis of lin-king point of dystrophin and acicul : n, the monoelonal antibodies of dys-trophin recognizig the N and C termini were used. The association domain seemed to be at both N and C terminals of dystrophin. The freeze etch electron microscopy disclosed that two different sized gold particles indicating cytoskeletons of aciculin and dystrophin were observed.