TM6 is not a domain, it is a helix. In the second link you posted, all trans-membrane helices are shaded in light blue, and labeled TM[1-7]. Then you have extracellular loops (ECL[1-3]) and intracellular loops (ICL[1-3]). The residues you want most likely are `PHTQ` in ICL3 that precedes TM6.



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