2D character arms that aren't a separate object look at mouse.

Ok, so I've made arms point towards the mouse before but they were always separate objects. This time I've a 2D character with a walk animation I've been working on for the past 2 hours. His arms move up and down when he walks. Now when my character picks up a gun I want his arms to stop moving up and down with the walk animation and point towards the mouse as one object (the same as the rest of the character). Is this even possible? Thanks.