def different_utr5_boundary(transcript1, transcript2):
    """Check if two transcripts have different UTR5 exon boundaries"""

    for i in range(len(transcript1.utr5_exons)):
        exon1 = transcript1.utr5_exons[i]
        exon2 = transcript2.utr5_exons[i]
        if exon1[0] != exon2[0] or exon1[1] != exon2[1]:
            return True
    return False