how to put an overline for \alpha_{KZ}

I want to put an overline over alpha_{KZ}, how do I do this?

This does not work:

ylabel('$\overline{U} (OH nm^{-2})$','FontSize',12)

Answer 1

[Stephen23]

ylabel('$\overline{\alpha_{KZ}}$','interpreter','latex')

[Jigar Faria]

It was very helpful.