def extract_interaction_labels(fasta_file):
    """
    Extracts the binary epitope and ppi annotations from the previously generated fasta files in epitope_dir and/or ppi_dir.   
    
    fasta_file format (3 lines): 

    >1HEZ_E                                                             (pdb identifier + optionally UNP <uniprot_id>)
    EVTIKVNLIFADGKIQTAEFKGTFEEATAEAYRYADLLAKVNGEYTADLEDGGNHMNIKFA       (protein sequence)
    0000000000000000000000011001100110011000000011111101100000000       (ppi/epitope annotations)
    
    """
    # Return None if there are no annotations
    if fasta_file is None:
        return None, None
    
    with open(fasta_file, 'r') as f:
        lines = f.readlines()
        annotations = lines[2].strip()
        annotations_list = [float(c) for c in annotations] # split into list
        fasta = lines[1].strip()
        return annotations_list, fasta