In this exercise we want to align two sequence against human hemoglobin using EBI's online version of needle.

1. Download the protein sequence of human hemoglobin alpha chain (accession: HBA_HUMAN).
2. Generate three global alignments of HBA_HUMAN with:
• HBB_HUMAN
• LGB2_LUPLU
• AAB37846
3. Are the sequences related?
4. From the alignment it is hard to tell any difference between the quality of the alignments of LGB2_LUPLU and AAB37846 compared to HBA_HUMAN. They both have a score around 40 and show only 40% to 20% similarity to hemoglobin. In fact, AAB37846 generates a spurious high-scoring alignment of a protein that has a completely different structure and function than hemoglobin.
• Can you show that HBA_HUMAN and LGB2_LUPLU are in fact related and have similar function although the sequence similarity is quite low?
• And that AAB37846 should not be considered to be related to HBA_HUMAN? (Hint: Pfam's sequence search allows to identify functional domains)