def graphprot_predictions_read_in_ids(predictions_file):
    """
    Given a GraphProt .predictions file, read in column 1 IDs in order
    appearing in file, and store in list.

    >>> test_file = "test_data/test.predictions"
    >>> graphprot_predictions_read_in_ids(test_file)
    ['SERBP1_K562_rep01_2175', 'SERBP1_K562_rep01_544', 'SERBP1_K562_rep01_316']

    """
    ids_list = []
    with open(predictions_file) as f:
        for line in f:
            cols = line.strip().split("\t")
            seq_id = cols[0]
            ids_list.append(seq_id)
    f.close()
    return ids_list