Table 1.

Estimated stoichiometry of palmitoylation

Picomoles of 3H-NEM per picomoles of subunit
Whole cell
BgtR α7 subunits in PC12 cells 1.0 ± 0.1a
α7 subunits in HEK cells 0.015b
5-HT3A subunits in HEK cells 1.2b
α7/5-HT3A subunits in HEK cells 1.4 ± 0.1ac
Subcellular fractions in PC12 cells
Cell-surface BgtR α7 subunits 0b
Intracellular BgtR α7 subunits 2.5b
Unassembled α7 subunits 0.6b
Subcellular fractions in HEK cells
Cell-surface BgtR α7/5-HT3A subunits 0.15 ± 0.03a
Intracellular BgtR α7/5-HT3A subunits 2.2 ± 0.3a
Unassembled α7/5-HT3A subunits 0.36 ± 0.04a
  • a Average ± SD; n = 3-4.

  • b Average of n = 2. Units: picomoles of 3H-NEM were determined by scintillation counting. Picomoles of subunits for BgtRs are equal to picomoles of 125I-Bgt bound at a stoichiometry of 4-5 pmol Bgt per pmol of receptor (Rangwala et al., 1997). To estimate the number of picomoles of subunits for α7, unassembled α7/5-HT3A, and 5-HT3A subunits in HEK cells, immunoblots of these subunits were quantified by densitometry and compared with blots of a known level of 125I-Bgt-bound α7/5-HT3A subunits. To estimate the number of picomoles of unassembled α7 subunits in PC12 cells, immunoblots of these subunits were quantified by densitometry and compared with blots of a known level of 125I-Bgt-bound α7 subunits.

  • c Measured 12 hr after transfection (Drisdel and Green, 2004).