Xiang Yu

We have investigated the mechanisms of assembly and transport to the cell surface of the mouse muscle nicotinic acetylcholine receptor (AChR) in transiently transfected COS cells. In cells transfected with all four subunit cDNAs, AChR was expressed on the surface with properties resembling those seen in mouse muscle cells (Gu, Y., A. F. Franco, Jr., P.D. Gardner, J. B. Lansman, J. R. Forsayeth, and Z. W. Hall. 1990. Neuron. 5:147-157). When incomplete combinations of AChR subunits were expressed, surface binding of 125I-alpha-bungarotoxin was not detected except in the case of alpha beta gamma which expressed less than 15% of that seen with all four subunits. Immunoprecipitation and sucrose gradient sedimentation experiments showed that in cells expressing pairs of subunits, alpha delta and alpha gamma heterodimers were formed, but alpha beta was not. When three subunits were expressed, alpha delta beta and alpha gamma beta complexes were formed. Variation of the ratios of the four subunit cDNAs used in the transfection mixture showed that surface AChR expression was decreased by high concentrations of delta or gamma cDNAs in a mutually competitive manner. High expression of delta or gamma subunits also each inhibited formation of a heterodimer with alpha and the other subunit. These results are consistent with a defined pathway for AChR assembly in which alpha delta and alpha gamma heterodimers are formed first, followed by association with the beta subunit and with each other to form the complete AChR.

According to the desire-satisfaction theory of well-being, your life goes well to the extent that your desires are satisfied. This theory faces the problem of prudential neutrality: it apparently cannot avoid saying that, from the point of view of prudence or self-interest, you ought to be neutral between satisfying an existing desire of yours and replacing it with an equally strong desire and satisfying the new desire. It also faces the problem of remote desires: it regards as directly relevant to your well-being even desires whose objects are intuitively too irrelevant to (or ‘remote’ from) your life to affect your welfare. In this article, I argue that desire theorists can answer both objections by appealing to hidden desires – ones that it is psychologically realistic to attribute to the agents in the cases on which the two problems are based, even though they are not mentioned in descriptions of those cases.