Related Experiment Video

Updated: Sep 12, 2026

Highly Sensitive Assay for Measurement of Arenavirus-cell Attachment
08:34

Highly Sensitive Assay for Measurement of Arenavirus-cell Attachment

Published on: March 2, 2016

The oligomerization reaction of the Semliki Forest virus membrane protein subunits

B U Barth1, J M Wahlberg, H Garoff

  • 1Department of Molecular Biology, Karolinska Institute, Novum, Huddinge, Sweden.

The Journal of Cell Biology
|February 1, 1995
PubMed

Insights

Semliki Forest virus (SFV) spike proteins p62 and E1 efficiently form heterodimers in cis during synthesis. This rapid association in the endoplasmic reticulum is crucial for viral structure and function.

Area of Science:

  • Virology
  • Molecular Biology
  • Cell Biology

Background:

  • The Semliki Forest virus (SFV) spike protein complex is essential for viral entry and is formed by heterodimers of p62 and E1 membrane proteins.
  • These subunits are synthesized sequentially from a single mRNA precursor, alongside the capsid protein (C), in the order C-p62-E1.

Purpose of the Study:

  • To investigate the process of spike protein heterodimerization for Semliki Forest virus (SFV) in BHK 21 cells.
  • To elucidate the mechanism and kinetics of p62-E1 subunit association during viral protein synthesis.

Main Methods:

  • Study of Semliki Forest virus (SFV) spike protein synthesis and assembly in BHK 21 cells.
  • Analysis of polyprotein processing, subunit association in the endoplasmic reticulum, and heterodimerization kinetics.

Main Results:

  • Polyprotein cleavage occurs during translation (cotranslational cleavage).
  • p62 and E1 subunits are initially unassociated in the endoplasmic reticulum.
  • Heterodimerization predominantly occurs between subunits synthesized from the same mRNA molecule (cis-heterodimerization) with rapid kinetics (t1/2 = 4 min) and high efficiency.

Conclusions:

  • A model for cis-directed heterodimerization is proposed, suggesting p62 retention at the translocation site until E1 synthesis and translocation.
  • p62 retention may involve its anchor sequence or association with protein folding machinery linked to the translocation apparatus.

More Related Videos

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes08:21

Visualization of HIV-1 Gag Binding to Giant Unilamellar Vesicle (GUV) Membranes

Published on: July 28, 2016

Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods10:40

Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods

Published on: December 21, 2019

Related Concept Videos

Protein Complex Assembly02:41

Protein Complex Assembly

Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.  Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Leaky Scanning02:28

Leaky Scanning

During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA.  Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
Intralumenal Vesicles and Multivesicular Bodies01:38

Intralumenal Vesicles and Multivesicular Bodies

Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
SNAREs and Membrane Fusion01:43

SNAREs and Membrane Fusion

Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle 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...
Inhibitors of Virion Maturation and Assembly01:19

Inhibitors of Virion Maturation and Assembly

As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...