Chord sequence
G7 C7 F7 B♭7 Amaj7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in A major
Over G7 · V7/♭III
Mode 4 of Melodic Minor
Over C7 · V7/♭VI
Over F7 · V7/♭II
Over Bb7 · subV7
Over Amaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.