Related Experiment Video
Updated: Aug 16, 2026

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay
Published on: October 19, 2012
Sec23p and a novel 105-kDa protein function as a multimeric complex to promote vesicle budding and protein transport
L Hicke1, T Yoshihisa, R Schekman
1Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
Abstract:
A cell-free protein transport reaction has been used to monitor the purification of a functional form of the Sec23 protein, a SEC gene product required for the formation or stability of protein transport vesicles that bud from the endoplasmic reticulum (ER). Previously, we reported that Sec23p is an 84-kDa peripheral membrane protein that is released from a sedimentable fraction by vigorous mechanical agitation of yeast cells and is required for ER to Golgi transport assayed in vitro. We have purified soluble Sec23p by complementation of an in vitro ER to Golgi transport reaction reconstituted with components from sec23 mutant cells. Sec23p overproduced in yeast exists in two forms: a monomeric species and a species that behaves as a 250- to 300-kDa complex that contains Sec23p and a distinct 105-kDa polypeptide (p105). Sec23p purified from cells containing one SEC23 gene exists solely in the large multimeric form. A stable association between Sec23p and p105 is confirmed by cofractionation of the two proteins throughout the purification. p105 is a novel yeast protein involved in ER to Golgi transport. Like Sec23p, it is required for vesicle budding from the ER because p105 antiserum completely inhibits transport vesicle formation in vitro.
Related Concept Videos
Intralumenal Vesicles and Multivesicular Bodies
Overview of Secretory Vesicles
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
SNAREs and Membrane Fusion
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
Vesicular Tubular Clusters
With the help of motor proteins such...
Protein Translocation Machinery on the ER Membrane
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Clathrin Coated Vesicles

