Dear all, I'm using psiblast to look at potential homologues of the subunits of a protein complex. Two of the subunits have significant hits (e-value < 0.0005) against the same 3 different proteins. Subunit A: ~800aa. Hits on region from ~500-800 hit on CCAAT displacement protein (residues 177-362) hit on BLACKJACK protein (residues 741-871) hit on Laminin gamma 1 precursor (residues 1293-1576) Subunit B: ~180aa. Hits along whole length of subunit. hit on CCAAT displacement protein (residues 181-341) hit on BLACKJACK protein (residues 763-886) hit on Laminin gamma 1 precursor (residues 1407-1532) The hits on the BLACKJACK region are in a region of 21 tandem repeats, in a region of coiled coil potential. The hits on Laminin are in a region which has no domain annotated, but is next to a region of consecutive 60aa repeats in a coiled coil structure. The hits on CCAAT are in a region annotated as CCAAT-like-domain, also just upstream of a coiled coil domain. Subunit A and Subunit B do not score significant hits on each other. In an all against all BLAST of Laminin, Blackjack,and CCAAT, all show significant similiarity (e-value < 1e-06). ------------------------------------ The questions I have are: How can I interpret the results of a hit on a region of tandem repeats? Do the tandem repeats render the score less valid? Can coiled-coil domains affect a sequence search score? Can I infer a relationship between the 2 subunits due to their common potential homologues? How can I investigate this scenario further? Many thanks for your time and suggestions, Richard _______________________________________________ Richard Harrington, HUS Graduate Vice-President, Men's Boat Club Captain, Homerton College. PhD student, Bioinformatics Group, MRC-Dunn Human Nutrition Unit, Cambridge University. e-mail: rah at mrc-dunn.cam.ac.uk telephone: +44 (0) 1223 252861 _______________________________________________