FRAP of different Z-band proteins in mature myofibrils. (A) The average FRAP recovery curves within 20 minutes of myotilin (black circles), cypher-1s (white circles), FATZ (black rectangles), cypher-2s (white rectangles), alpha-actinin (black triangles), actin in the Z-band (white triangles) and telethonin (black diamond). (B) Comparison of the fast (solid black columns) and slow mobile (stippled columns) fractions of different Z-band proteins. Values are the means ± SDs. Note that myotilin and cypher-1s were 100% mobile, and telethonin is the slowest protein recovering from photobleaching.