AK makes TPTK and faces donk bet on turn

[HouseCalls]

Donk bettor is 77/7.8/.8 after 77 hands - he has 7BB left after his bet
Donk bet caller is 45/1.4/1.4 after 71 - she has 6BB left after her call

Full Tilt Poker $0.25/$0.50 Limit Hold'em - 9 players
Hand Converter Tool from DeucesCracked.com

Preflop: Hero is MP2 with K[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/diamond.gif[/img]
UTG+1 folds, UTG+2 calls, MP1 calls, <font color="#FF0000">Hero raises</font>, CO folds, Button folds, SB folds, BB calls, UTG+2 calls, MP1 calls.

Flop: (8.40 SB) K[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/diamond.gif[/img], 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG+2 checks, MP1 checks, <font color="#FF0000">Hero bets</font>, BB calls, UTG+2 calls, MP1 calls.

Turn: (6.20 BB) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#FF0000">BB bets</font>, UTG+2 folds, MP1 calls, Hero??

What's your play and your plan for the river?