Table 1. M2-cap Sequence Alignment of Cys-loop receptors.
subunit | 18′ | 19′ | 20′ | 21′ | 22′ | 23′ | 24′ | 25′ | 26′ | 27′ | 28′ |
AChR α1 | I | V | E | L | I | P 265 | S | T | S | S | A |
AChR α2 | I | T | E | I | I | P 276 | S | T | S | L | V |
AChR α3 | I | T | E | T | I | P 269 | S | T | S | L | V |
AChR α4 | I | T | E | I | I | P 279 | S | T | S | L | V |
AChR α5 | I | T | E | T | I | P | S | T | S | L | V |
AChR α6 | I | T | E | T | I | P 274 | S | T | S | L | V |
AChR α7 | V | A | E | I | M | P 264 | A | T | S | D | S |
AChR α9 | V | A | E | I | M | P 102 | A | S | E | N | V |
AChR α10 | L | A | E | S | M | P 270 | P | A | E | S | V |
AChR β1 | L | A | D | K | V | P 276 | E | T | S | L | A |
AChR β2 | I | S | K | I | V | P 265 | P | T | S | L | D |
AChR β3 | I | E | E | I | I | P 270 | S | S | S | K | V |
AChR β4 | I | S | K | I | V | P 262 | P | T | S | L | D |
AChR δ | I | S | K | R | L | P 279 | A | T | S | M | A |
AChR γ | V | A | K | K | V | P 274 | E | T | S | O | A |
AChR ε | I | A | Q | K | I | P 275 | E | T | S | L | S |
GABA α1 | A | R | N | S | L | P 304 | K | V | A | Y | A |
GABA α2 | A | R | N | S | L | P 305 | K | V | A | Y | A |
GABA α3 | A | R | N | S | L | P 330 | K | V | A | Y | A |
GABA α4 | A | R | H | S | L | P 337 | K | V | S | Y | A |
GABA α6 | A | R | H | S | L | P 284 | K | V | S | Y | A |
GABA β1 | L | R | E | T | L | P 298 | K | I | P | Y | V |
Gly α1 | S | R | A | S | L | P 299 | K | V | S | Y | V |
Gly β | L | A | A | E | L | P 321 | K | V | S | Y | V |
5HT 3A | V | S | D | T | L | P 278 | A | T | A | I | G |
5HT 3B | M | S | D | E | V | P 289 | R | S | A | G | C |
The entire sequence for the AChR α1 subunit (IVELIPSTSSA) is conserved in all vertebrates. Position 23′ is a proline (bold) in all cys-loop receptors. The superscripts on the conserved Pro represent the residue number.