Most likely your antibody is not specific for our target.
(e.g. see BAKER M., p. 274, NATURE. VOL 521 Date: 21 MAY 2015.)
Other possible explanations would be modifications of human FUS in your experimental system (tissue, cell type etc.) or the generation of aggregates, intermediates with other cofactors of post-transcriptional, modifications of the protein monomer/dimer ... itself etc.
Hi as per you uniprot ID please check propelry as its molecular weight in uniprot is 75 only. check this it will help you https://www.abcam.com/tlsfus-antibody-ab23439.html
I agree with Mahedras information (e.g. see infos at https://www.uniprot.org/uniprot/P35637. or https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=DetailsSearch&Term=2521).
Moreover, an alternative synonym is "75 kDa DNA-pairing protein".
Andreas Eisenreich Thank you, whilst I appreciate your answer, if you plug in the FASTA sequence you still only have a Mass (Da):53,426. I'm most likely missing something.