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Volume 154, Issue 21 w! i4 T1 s5 w0 A& ^! L# L
On the cover: In this issue of Cell, Terasaki et al. (pp. 285–296) 6 b8 ?4 h a! Y9 g, }; [
explain how parallel sheets of endoplasmic reticulum are connected. The 8 F! w: i3 S \) |9 M5 Q9 f
existence of these sheet stacks and their function in synthesis of membrane and 9 t9 n7 _* o/ R
secreted proteins has been known for more than 60 years. Three-dimensional
6 M4 v4 c5 x3 [7 j- x# p% L2 ]reconstructions from serial section electron micrographs from mouse salivary
1 Z# F9 n* N. e. C& I4 Kgland show that the sheets are connected by twisted membrane surfaces with
) v! ?0 r/ D5 O- Q. }; D7 Lhelical edges. The overall structure resembles a parking garage, in which the ' n3 I' S: `4 A- t5 B- V, W4 m
different levels are connected by helicoidal ramps. Theoretical calculations 5 N) M% ]6 @# ~- T# F
show that this structure minimizes the elastic energy of sheet edges and - i; l+ n/ i& ~- L% \& K
surfaces and allows dense packing of this organelle in the restricted space of a
8 j3 g* a8 _2 vcell.7 E6 ~" c {. P& b
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发表于 2013-7-19 19:50
发表于 2013-7-19 20:06
