Depreciation

If you still own the building, it should not have an adjusted basis.

Of course the store has an adjusted tax basis. It's the original cost, less the depreciation taken to date. The real question should be whether the depreciation of the store - now, as a rental property - starts over, or just continues at the same rate, life, percent, whatever...

You asked about "the adjusted basis after the sale...." You didn't sell the building, you sold a business that was run out of the building. The sale of the business has nothing to do with the basis of the building, so the building has no adjusted basis.

The remaining (adjusted) cost basis of the building on your tax accounting books' balance sheet should be the original cost of the building, adjusted (reduced) by the amount of depreciation taken on the building during the time you used it (and depreciated it) in your pet supply business. I take it that your question is how should you, now that it has become a rental property, depreciate that remaining, adjusted tax basis - the building part, and not the land.

It seems to me like it's pretty much perfectly straight forward double-entry tax accounting. Of course the building has a tax basis, and of course that basis has been reduced by the amount of depreciation already taken on the building. And the question is how to now claim depreciation on the building during its use in your rental activity.

I can definitely agree with that.