Related Experiment Video
Updated: Jul 3, 2026
16:43
Visualization of Endoplasmic Reticulum Subdomains in Cultured Cells
Published on: February 18, 2014
Sec16 is a determinant of transitional ER organization
Pamela L Connerly1, Masatoshi Esaki, Elisabeth A Montegna
1Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, Illinois 60615, USA.
Current Biology : CB
|August 23, 2005
Summary
Sec16 protein is essential for organizing endoplasmic reticulum (ER) exit sites in Pichia pastoris. Disruption of Sec16 leads to ER exit site fragmentation and Golgi disruption, highlighting its role in protein export.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Proteins are exported from the endoplasmic reticulum (ER) via COPII vesicles that bud from transitional ER (tER) sites.
- The mechanisms concentrating COPII components at tER sites remain poorly understood.
- Pichia pastoris offers a model system with distinct tER sites for studying tER organization.
Purpose of the Study:
- To investigate the role of Sec16 in the organization and integrity of tER sites in Pichia pastoris.
- To determine if Sec16 is required for the concentration of COPII components at tER sites.
Main Methods:
- Utilized a temperature-sensitive Sec16 mutant in Pichia pastoris.
- Observed tER site integrity and COPII vesicle formation.
- Inhibited COPII assembly using a dominant-negative Sar1 GTPase mutant.
- Assessed Golgi structure in wild-type and mutant strains.
Main Results:
- Sec16 is crucial for maintaining tER site integrity in P. pastoris.
- Sec16 is less abundant than COPII coat proteins at tER sites and exhibits saturable binding.
- A temperature-sensitive sec16 mutation causes tER fragmentation and Golgi disruption at elevated temperatures.
- Inhibition of COPII assembly does not affect tER site integrity, indicating Sec16's specific role.
Conclusions:
- Sec16 acts as an organizational factor, clustering COPII coat proteins to form tER sites.
- Proper tER organization, dependent on Sec16, is essential for maintaining Golgi structure in budding yeast.
Related Concept Videos
01:51Determination
During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. Specification is demonstrated by removing a segment of an early embryo, “neutrally” culturing the tissue in vitro—for example, in a petri dish with simple medium—and then observing the derivatives. If the cultured region gives rise to cell types that it would normally generate in the embryo, this means that it is specified. In contrast, determination...
01:29Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
01:27Post-translational Translocation of Proteins to the RER
A sizable fraction of proteins destined for ER are first synthesized in the cell cytosol and then transported across the ER membrane–a process called post-translational translocation. Similar to cotranslationally translocated proteins, these proteins also use the Sec translocon complex to enter the ER lumen.
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
Targeting proteins to the ER
Hsp40 and Hsp70 chaperone molecules bind the translated proteins in the cytosol to prevent their folding. The chaperone binding helps to keep the signal...
01:26Transport Across the Golgi
While it is unclear how molecules move between adjacent Golgi cisternae, it is apparent that the molecules move from cis- cisterna, the entry face, to the trans- cisterna, the exit face. Experiments initially suggested vesicles that bud from one cisterna and fuse with the next cisterna to transport proteins between the cisternae. This vesicular transport model describes the Golgi apparatus as a relatively static structure with a unique enzyme composition in each cisterna. Molecules are...
01:28Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into 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.
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.
01:28Forced Transdifferentiation
Transdifferentiation, also known as lineage reprogramming, was first discovered by Selman and Kafatos in 1974 in silkmoths. They observed that the moths’ cuticle-producing cells transformed into salt-producing cells. Many such cases of natural transdifferentiation occur in organisms. In humans, pancreatic alpha cells can become beta cells. In newts, the loss of the eye’s lens causes the pigmented epithelial cells to transdifferentiate into the lens cells.
Artificial transdifferentiation occurs...
Artificial transdifferentiation occurs...