I have a gridview with a HyperLink column - how can I convert this to a LinkButton?

Currently the URL from the hyperlink causes the page to reload different information in a separate section. I am converting this to a partial postback - for this to work I need to use a POST operation rather than a link.

The problem I have is how exactly do I detect the ID from the element in the grid as I no longer have a QueryString like ?id=1 to work with.

I have set up a CommandName on the button and hooked up the RowCommand event on the back end - but I can't see how to get the ID?