文摘
The hydrophobic transmembrane domain of glycophorin A contains a sequence motif thatmediates dimerization in membrane environments. Long-range interhelical distance measurements usingmagic angle spinning NMR spectroscopy provide high-resolution structural constraints on the packing ofthe dimer interface in membrane bilayers. We show that direct packing contacts occur between glycineresidues at positions 79 and 83 in the transmembrane sequence. Additional interhelical constraints betweenIle76 and Gly79 and between Val80 and Gly83 restrict the rotational orientation and crossing angle ofthe interacting helices. These results refine our previously proposed structure of the glycophorin A dimer[Smith, S. O., and Bormann, B. J. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 488-491] which revealed thatthe methyl groups of Val80 and Val84 are packed against Gly79 and Gly83, respectively.