BB vs UTG, SRP, Straight, Range UTG??

Yeah beside raising a little bigger on the flop nothing much to do here. Just a cooler.

Defending seems a little bit loose out of position, but the rest of the hand seems alright to me with the straight.

Cheers,
SDK1987

3bet pre OOP. You can even 4bet this combo.
Flop raise is fine. No slowplay.
Cant fold this hand. Ever. Shove, call do whatever you want.

Let's explore the river bet. When you x/r a flop and bet OTT there won't be many AK hands that happily call OTT, except AcKc.

1. Pessimistic range
Villain has: boats and bigger straight with 76s, also A2s, only 1 combo of AcKc and AA. Btw, AA in this range already might be loose, but people don't like folding AA, so it's fine (maybe).

Board: 4♦5♣3♣ 3♥ K♥
       Equity     Win     Tie
MP3    73.81%  66.67%   7.14% { KK+, 55-33, A2s, 76s, AcKc }
BB     26.19%  19.05%   7.14% { As2s }

As you can see, we have 22% equity and can't value bet if this range is true.

2. Slightly more optimistic range
Added all AK (which shouldn't likely call OTT).

Board: 4♦5♣3♣ 3♥ K♥
       Equity     Win     Tie
MP3    53.45%  48.28%   5.17% { KK+, 55-33, AKs, A2s, 76s, AKo }
BB     46.55%  41.38%   5.17% { As2s }

Now you have 46% equity, but we need 50% + to value bet.

3. Somewhat optimistic range without AK, but added QQ and JJ.
I kept AcKc ofc.

Board: 4♦5♣3♣ 3♥ K♥
       Equity     Win     Tie
MP3    46.97%  42.42%   4.55% { JJ+, 55-33, A2s, 76s, AcKc }
BB     53.03%  48.48%   4.55% { As2s }

This seems to be a value bet with 53% equity. Quite close, though. We still have to pay rake and lose some of the value.

Conclusion: If opponent is someone on the tighter side you don't have a value bet. It's not like I'd be super happy to call down with QQ, where you have all the boats and straights.
Look:

Board: 4♦5♣3♣ 3♥ K♥
       Equity     Win     Tie
MP3    51.47%  51.47%   0.00% { QQ }
BB     48.53%  48.53%   0.00% { 55-33, 76s, AcQc, KcQc, AcJc, KcJc, QcJc, AcTc, KcTc, QcTc, JcTc, Ac9c, Kc9c, Qc9c, Jc9c, Tc9c, Ac8c, Kc8c, Qc8c, Jc8c, Tc8c, 9c8c, Ac7c, 9c7c, 8c7c, Ac6c, Ac5c, Ac4c, Ac3c, As2s }

You would have to over bluff a lot as well.

NB! Villain might or might not have 33-55 preflop. It depends.

Ooops, made a mistake with QQ. I would need you to bluff with 7-8 combos of busted Acxc, f.e. to call down.

About preflop : folding A2s BB vs MP (if I read well the positions) against 2,5x is out of the question. 3betting is possible but often overplay. There is nothing wrong with calling that combo pre, really.

About postflop (river) : interesting point by AthleticAZ but I'd be on the optimistic side of the force for the ranges. Then again I could have to rethink that.