looking for commercially-available high MW protein

[peng.zhixiang at uvm.edu]

Hi, 
I am working with a protein which shows an approximately 470 kDa band
in Western blotting .My problem is, I do not know if there is a
protein around 450~500  kDa that are commercially available. Does
anybody know such protein standards or a purified protein, ideally of
around 470 kDa, which is supplied by manufacturers?
Thanks in advance for advice!

peng.zhixiang at uvm.edu