Born Autry DeWalt Mixon Jr., singer and saxophonist Junior Walker flamboyantly led an eponymous Motown ensemble, whose 1965 entry “Shotgun” became their sizzling signature. The group's party-ready R&B and soul ran across two decades' worth of output, including a roughened-up cover of the Marvin Gaye hit “How Sweet It Is (To Be Loved By You),” complete with loose call-and-response harmonies. Walker stepped up the hip-shaking funk for “Do the Boomerang” while softening his sax for the sultry ballad “What Does It Take (To Win Your Love).” Most often, though, he soundtracked such sweaty nights out as the one depicted in “Shake and Fingerpop.”