Vol. 151, No. 4, April 1, 2019. 10.1085/jgp.201812215.

After publication of this article, several errors were brought to the authors’ attention, which have been corrected as follows, with bold indicating insertions and strikethrough indicating deletions.

In the Results section “Other receptors,” the asterisk in Eq. 5 should have been in the denominator, and some percentages have been adjusted:

“Next, we investigated energy efficiency in other receptors. In terms of equilibrium constants, Eq. 2 is
$η=1−log(KdR)/log(KdR*),$
(5)
where KdR* is the equilibrium dissociation constant of the active conformation and KdR is the equilibrium dissociation constant of the resting conformation (Fig. 1 b). For example, KdR* and KdR for ACh measured at the mouse AChR α−ε site are 12 nM and 153 µM (Nayak and Auerbach, 2017), from which we calculate ηACh = 5352%.

We used Eq. 5 to estimate the efficiency of the agonist Ca2++2 at binding sites of KCa1.1 (BK; a potassium-selective ion channel)using published values of the equilibrium dissociation constants (Sweet and Cox, 2008). At Ca-bowl sites, KdR = 3.1 mM and KdR* = 0.9 µM, from which we calculate ηCa = 649%. At RCK1 sites, KdR = 15.8 mM and KdR* = 2.1 µM, from which we calculate ηCa = 6813%.”

In the Discussion section “η and ∆G0,” two sentences were deleted:

“Table 5 shows η values for different agonist/site combinations and ΔG0 values for seven kinds of receptor. The overall, average

efficiency for the native agonist was ∼51%, with values ranging between 39% (GABAA receptors) and 59% (glycine receptors). Human endplate AChR-binding sites are typical in this regard, with an average efficiency of ∼51%. Apparently, many diverse receptors dedicate about half of the available ligand-binding energy to the activation conformational change. Ca2+at KCa1.1-binding sites is substantially less efficient, for unknown reasons. It is possible that the low per-site efficiency is compensated by the large number of binding sites (n = 8).