Mammalian Sec23p homologue is restricted to the endoplasmic reticulum transitional cytoplasm.

AUTOR(ES)

Orci, L

RESUMO

The yeast Sec23 protein is required in vivo and in vitro for transport of proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. Ultrastructural localization of the Sec23p mammalian homologue (detected by antibody cross-reaction) in exocrine and endocrine pancreatic cells shows a specific distribution to the cytoplasmic zone between the transitional ER cisternae and Golgi apparatus where it appears associated with the tubular protuberances of the transitional ER cisternae, as well as with a population of vesicles, and surrounding cytoplasm. When ER-Golgi transport is interrupted with an energy poison, protuberances and transfer vesicles markedly decrease but Sec23p immunoreactive sites remain in the transitional cytoplasm not apparently tethered by membrane attachment. This unanticipated degree of organization suggests that cytosolic proteins, such as Sec23p, may be retained in specialized areas of the cytoplasm. A structure within the transitional zone may organize the flux of transport vesicles and Sec proteins so as to ensure efficient protein traffic in this limb of the secretory pathway.

Documentos Relacionados

• Yeast Sec23p acts in the cytoplasm to promote protein transport from the endoplasmic reticulum to the Golgi complex in vivo and in vitro.
• Sec23p and a novel 105-kDa protein function as a multimeric complex to promote vesicle budding and protein transport from the endoplasmic reticulum.
• COPII coat subunit interactions: Sec24p and Sec23p bind to adjacent regions of Sec16p.
• Sec61p is part of the endoplasmic reticulum-associated degradation machinery
• Arabidopsis Sec21p and Sec23p Homologs. Probable Coat Proteins of Plant COP-Coated Vesicles1