Edit Window and Mix Window Keyboard Shortcuts : Playback

Playback
 
Control+Spacebar, or Option-click, on Transport Play button
Start+Spacebar, or Alt-click on Transport Play button
Command+J, or Option+Spacebar
Left/Right Arrow keys (when selection exceeds window view)
Left/Right Arrow keys (when selection exceeds window view)
Back/Forward (move the playback location backwards/forwards by the Back/Forward amount) (Pro Tools HD and Pro Tools with Complete Production Toolkit only)
Command+Transport Rewind button or Transport Fast Forward button
Ctrl+Transport Rewind button or Transport Fast Forward button
Back/Forward and Play (move the playback location backwards/forwards by Back/Forward amount and then begin playback) (Pro Tools HD and Pro Tools with Complete Production Toolkit only)
Command+Option+Transport Rewind button or Transport Fast Forward button
Ctrl+Alt+Transport Rewind button or Transport Fast Forward button
Extend a selection backwards by the Back/Forward amount (Pro Tools HD and Pro Tools with Complete Production Toolkit only)
Shift+Command+Transport Rewind button or Transport Fast Forward button
Shift+Ctrl+ Transport Rewind button or Transport Fast Forward button
Extend the selection backwards by the Back/Forward amount and begin playback (Pro Tools HD and Pro Tools with Complete Production Toolkit only)
Shift+Command+Option+Transport Rewind button or Transport Fast Forward button
Shift+Ctrl+Alt+Transport Rewind button or Transport Fast Forward button
Command+Shift+L, or Control-click on Transport Play button
Transport Master toggle (Pro Tools/Machine/MMC)