I tried to perform RNA immunoprecipitation assay to reveal RNA partners of the desired protein. Can I store cell extract not the lysate- after cross-linking (1% FA, 10 min RT)- at -80 degrees? Best.
Probably yes. The important thing is that Formaldehyde is deactivating ~all enzymes. Ice crystal formation and thawing might cause some damage to proteins and protein complexes, though.
Do you actually mean fixed cells or already lysed cells? But that should not matter much.