Fig. 1. Longitudinal variation in myosin heavy chain (MyHC) expression detected by high resolution SDS-PAGE. (A) Superior rectus muscle was cut into six parts as shown. The approximate location of the endplate band region (EPB) is marked. (B) Myofibrils prepared from each region identified in A were analyzed by SDS-PAGE and stained with Coomassie Blue G-250. The bands were identified by comparison with the migration positions in muscles of known myosin composition (Briggs and Schachat, 2000), and as described in Materials and methods. EO myosin is MYH13. (C) Relative amounts of each MyHC were determined by scanning with visible light and densitometry.