periplastidal compartment
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2014 ◽  
Vol 22 ◽  
pp. 88-93 ◽  
Author(s):  
Christopher Grosche ◽  
Franziska Hempel ◽  
Kathrin Bolte ◽  
Stefan Zauner ◽  
Uwe G Maier

2012 ◽  
Vol 11 (12) ◽  
pp. 1472-1481 ◽  
Author(s):  
Simone Stork ◽  
Daniel Moog ◽  
Jude M. Przyborski ◽  
Ilka Wilhelmi ◽  
Stefan Zauner ◽  
...  

ABSTRACT Protein import into complex plastids of red algal origin is a multistep process including translocons of different evolutionary origins. The s ymbiont-derived E RAD- l ike ma chinery (SELMA), shown to be of red algal origin, is proposed to be the transport system for preprotein import across the periplastidal membrane of heterokontophytes, haptophytes, cryptophytes, and apicomplexans. In contrast to the canonical endoplasmic reticulum-associated degradation (ERAD) system, SELMA translocation is suggested to be uncoupled from proteasomal degradation. We investigated the distribution of known and newly identified SELMA components in organisms with complex plastids of red algal origin by intensive data mining, thereby defining a set of core components present in all examined organisms. These include putative pore-forming components, a ubiquitylation machinery, as well as a Cdc48 complex. Furthermore, the set of known 20S proteasomal components in the periplastidal compartment (PPC) of diatoms was expanded. These newly identified putative SELMA components, as well as proteasomal subunits, were in vivo localized as PPC proteins in the diatom Phaeodactylum tricornutum . The presented data allow us to speculate about the specific features of SELMA translocation in contrast to the canonical ERAD system, especially the uncoupling of translocation from degradation.


2010 ◽  
Vol 27 (7) ◽  
pp. 1538-1545 ◽  
Author(s):  
Yoshihisa Hirakawa ◽  
Gillian H. Gile ◽  
Shuhei Ota ◽  
Patrick J. Keeling ◽  
Ken-ichiro Ishida

1982 ◽  
Vol 60 (11) ◽  
pp. 2440-2452 ◽  
Author(s):  
Lisa McKerracher ◽  
Sarah P. Gibbs

An ultrastructural investigation of cell and nuclear division in Cryptomonas sp. (θ) was made with particular emphasis on the mode of division of the chloroplast and nucleomorph. Mitosis is similar to that in other cryptomonads except that the nuclear envelope remains mostly intact. Division of the single chloroplast occurs in preprophase by constriction through the dorsal bridge. Frequently there is a lag between the division of the chloroplast and the division of its envelope of chloroplast endoplasmic reticulum. In addition, the inner membrane of the chloroplast endoplasmic reticulum may infold well in advance of the outer membrane.The nucleomorph is a unique double membrane limited organelle which is found in the periplastidal compartment of cryptomonads. It divides in preprophase following basal body replication but before division of the chloroplast and its chloroplast endoplasmic reticulum is complete. The inner membrane of the nucleomorph envelope invaginates first forming a double membraned baffle. The outer membrane invaginates next and completes division. Microtubules are not involved in nucleomorph division. None were observed and colchicine, which inhibited nuclear division, did not inhibit nucleomorph division. The theory that the nucleomorph is the residual nucleus of a former eukaryotic endosymbiont is reevaluated in light of these new observations.


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