Thanks to both of you for the advice.The protein stoichiometry of PFK- phosphofructokinase in muscle is gives as Homo-2-mer.Whereas in uniprot it is mentioned PFK exists as a tetramer and M4 is the active form in muscle.
I am a little confused.Is the protein structure a Homo-2mer or a tetramer?
As mentioned in one of the answers, PDB is the repository for resolved structures. You may be able to use Uniprot or PDB to find related structures to any given PDB (though I don’t have specific info on how). It the same protein has been resolved in several forms, I would expect them to be linked somehow.