def _mergeProteinEntries(proteinLists, protToPeps):
    mergedProtToPeps = dict(protToPeps)
    for proteins in proteinLists:
        for protein in proteins:
            peptides = mergedProtToPeps.pop(protein)
        mergedProtein = tuple(sorted(proteins))
        mergedProtToPeps[mergedProtein] = peptides
    return mergedProtToPeps