Please read Alexey Sklyarenko's annotations on Pale Fire, Ada and other Nabokov works here.
In his Commentary to Shade's poem Kinbote (in VN's novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions the poet's mother, née Caroline Lukin, and points out that Lukin comes from Luke, as also do Locock and Luxon and Lukashevich: