Opp is a TAG running 12/10/2.7 over 120 hands

Full Tilt No-Limit Hold'em, $0.25 BB (9 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

UTG ($25.70)
UTG+1 ($12.25)
Hero (MP1) ($28.20)
MP2 ($24.15)
MP3 ($50.20)
CO ($13.90)
Button ($24.40)
SB ($37.50)
BB ($19.75)

Preflop: Hero is MP1 with A, A
UTG raises to $0.85, 1 fold, Hero raises to $2.50, 6 folds, UTG calls $1.65

Flop: ($5.35) 5, 8, 2 (2 players)
UTG checks, Hero bets $4, UTG calls $4

Turn: ($13.35) K (2 players)
UTG checks,

Hero checks behind? bet/calls? bet/folds? What amount do we bet?