[smghz]

I honestly don't know what a binding partner means. When I googled it only literature showed up. What does it mean, and is it related to complexes? thanks.

[Irlanur]

I guess that is again one of these chemist's terms which is intuitively no problem but the exact definition might not be that easy. It is just something that binds to something else. For example in complexes.

A more physical try: X is a binding partner of Y if it sits in an energy minimum which is closer than infinity.

[Babcock_Hall]

Here are some examples of how I would use that word in biochemistry:  The binding partner of epinephrine is a particular beta-adrenergic receptor.  The binding partner of anti-A antibodies is the A-antigen (a particular glycolipid) on red blood cells.  A binding partner of hexokinase is ATP.  I don't, however, think that one should restrict that term to biochemistry.