A hypothetical family of proteins consists of six similar but different proteins. Each of the six proteins can form transcription factors by forming homo- or heterodimers in combinatorial mixtures, each binding to different regulatory sites
Calculate the number of different dimeric structures that can be formed from the six proteins (and, thus, potential number of different regulatory sites that can be bound).
21
Label the proteins 1-6, 1 can bind with 1 (1+1), 1 can bind with 2 (2+2), etc.
(1+1), (1+2), (1+3), (1+4), (1+5), (1+6)
(2+2), (2+3), (2+4), (2+5), (2+6)
(3+3), (3+4), (3+5), (3+6)
(4+4), (4+5), (4+6)
(5+5), (5+6)
(6+6)
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