International
Tables for
Crystallography
Volume B
Reciprocal space
Edited by U. Shmueli

International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 387

Figure 2.5.7.7 

P. A. Penczekg
[Figure 2.5.7.7]
Figure 2.5.7.7

Hrs (blue) embedded into the membrane (yellow) of an early endosome. Two functional domains have been docked into the cryo-EM density map of hexameric Hrs, determined to 16 Å resolution, and are shown as ribbons coloured by secondary structure (Pullan et al., 2006[link]). The structures of the VHS and FYVE domains have been determined crystallographically (Mao et al., 2000[link]) and are docked into the EM density map of the Hrs. The knowledge of the location of the FYVE and VHS domains, which are reported to bind to PI(3)P molecules found within the endosomal membrane (Kutateladze et al., 1999[link]), has guided the hypothetical placement of Hrs within the endosomal membrane. The immersion of the end caps of Hrs into the endosomal membrane demonstrates an `end-on' binding model of the Hrs particles with the membrane. According to this model, either end cap can embed into the membrane, allowing the other end cap to carry out other essential protein trafficking functions, or to embed into another membrane, thus preventing fusion of membranes during early endosomal fusion.