sentence: The most important putative molecular switches are the ionic lock involving the conserved DRY motif at third transmembrane helix ( TM3 ) and 6.30 and / or 6.34 residue ( Ballesteros-Weinstein notation [ 31 ] ) from TM6 , 3 – 7 lock switch constituted by 3.28 and 7.43 residues from TM3 and TM7 , respectively , the transmission switch involving the Trp residue from the conserved CWxP motif , tyrosine toggle switch involving Tyr 7.53 from NPxxY motif [ 28 ] , and the hydrophobic barrier , preventing water from establishing a continuous chain through an inactive receptor and broken upon activation [ 32 ] .