SUBSTITUTING YOGHURT IN BANANA CAKE RECIPE???

I have a awesome recipe I sue for banana cake (Jo Seagar) but I have no yoghurt to make this? ? ? Does anyone know a suitable substitute? ? ?
The recipe goes like this:
1 C sugar
100gm Butter (melted)
3 mashed bananas
3 eggs
1 tsp baking soda
1/2 C milk (warm the milk and stir in baking soda to dissolve)
150ml youghurt
2 C self-raising flour

Mix sugar, butter, banana and eggs together. Warm milk and stir in baking soda. Add with yoghurt to egg mixture then stir in flour.
Pour into sprayed and lined tin and bake on 160c for 50 mins.

Its an awesome recipe that has never failed me but I need to know waht I can substitute the yoghurt for. I have heard that milk and sour cream but what would be the measurements or proportions for this recipe. What about sour cream? ? ? I have about half a 250g pottle of sour cream in the fridge? ? ? Can I just do a straight swap? ? ? What exactly is the function f the yoghurt too? ? ? Is that the reason the cake is moist? ? ?
Thanks! ! !

Yes you can substitute the yogurt with sour cream no probs.

There are many cake recipes where the ingredients are identical apart from some using sour cream & some using yogurt.

Hey cool thanks... .

or buttermilk, I buy a carton of bm and freeze in smaller lots so I always have some and it makes baking so light. And thanks for the recipe I have 3 'brown' bananas so might make this today, does this keep well. I usually make the 'ladies a plate' recipe and keeps well, it has coffee essense in it so really nice too.

The yoghurt (or sour cream) provides some acid, so that the baking soda will activate, which lightens the cake. Soured milk works too (milk with a few drops of either vinegar or lemon juice) :-)

Ahhh ok... . I get it... . oh and yes this cake does keep well... . never lasts long enough usually but I just keep it in a air tight container... . I have had some pieces stored in just one of those glad containers and I could still eat it 5 days later and still moist... . so yeah its a good recipe! ! ! I must remember the milk with vinegar if I dont have yoghurt or sour cream... . in fact that would be easier to be honest and probably cheaper... . If I have half a cup of milk... . would that be about a 1tsp of vinegar? ? ?

For 1/2 cup of milk, I would use 1/2 tsp of vinegar or lemon juice. It will go lumpy and horrible looking, don't worry about that, and just give it one wee stir ... don't over mix the acid into it. :-)

Thanks! ! !