USA Olympic gold-medal winner Sylvia Fowles has grabbed most of the headlines for Spartak in her rookie campaign with the two-time defending champions, but Jackson had 33 points and eight rebounds in Wednesday's win in Istanbul.
Jackson, whose previous high this season had been the 19 she scored against Fenerbahce in the second week, drilled five of 10 shots from behind the arc and Diana Taurasi nailed six of nine on her way to 22 points for Spartak, who delivered a first-quarter knockout by outscoring Fener 29-15.
They extended the lead to 53-35 by half-time and cruised the rest of the way to improve to 7-1 in Group D.
László Rátgéber's team also got 14 points and 11 rebounds from the excellent point guard Sue Bird.
In 18 minutes, meanwhile, Fowles had two points and three boards - far below her season averages of 15.1 and 10.1.
Tammy Sutton-Brown led Fenerbahce (5-3) with 18 points.