elution of co-IP from protein G beads

[AK]

Dear experts, I am doing a co-immunoprecipitation experiment. I pull down 
protein X with a mAb and detect co IP of protein Y with pAb. protein Y is 
heat sensitive and if I heat (~70C) the sample to elute immune complex, I 
can not detect protein Y. without heating, protein-G beads do not let the 
IgG chains loose, at least. Are there other ways to elute immune complex 
without heating? of course low pH is one obvious strategy that I have not 
tried yet. thank you in advance.
AK