Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Complement System01:27

Complement System

The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...
Protein Complexes with Interchangeable Parts01:57

Protein Complexes with Interchangeable Parts

Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
Caspases01:24

Caspases

Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...
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...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

BMN 349, a small molecule inhibitor of Z alpha-1 antitrypsin polymerization, increases secretion and reduces intrahepatic inclusions in a mouse model of disease.

Hepatology (Baltimore, Md.)·2026
Same author

Exploiting a Cryptic Pocket in DsbA through Structure-Guided Parallel Synthesis and Direct-to-Biology Screening.

Journal of medicinal chemistry·2026
Same author

Synaptic and cytoskeletal CSF signatures of motor neuron disease: the role of cyclase-associated protein 2.

Scientific reports·2026
Same author

<i>Helicobacter pylori</i> induces the production of interleukin-37 to promote broad immunosuppression and enhance colonization.

Gut microbes·2026
Same author

Characteristics of T-Cells Expressing IL-37 and Its Receptors in Inflammatory Bowel Disease.

International journal of molecular sciences·2026
Same author

Structural basis for uPAR binding to an antibody developed for targeted cancer therapy. Mechanistic insights into flexibility, ligand recognition, and molecular imaging.

Protein science : a publication of the Protein Society·2026

Related Experiment Video

Updated: May 12, 2026

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment
07:26

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment

Published on: July 18, 2017

A molecular switch governs the interaction between the human complement protease C1s and its substrate, complement

Andrew J Perry1, Lakshmi C Wijeyewickrema, Pascal G Wilmann

  • 1Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, Victoria 3800, Australia.

The Journal of Biological Chemistry
|April 18, 2013
PubMed
Summary
This summary is machine-generated.

The complement system

Keywords:
ActivationC1sC4ComplementCrystal StructureEnzyme StructureProteaseSerine ProteaseZymogen

More Related Videos

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion
06:54

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion

Published on: June 15, 2019

Characterizing Modulators of Protease-Activated Receptors with a Calcium Mobilization Assay Using a Plate Reader
07:13

Characterizing Modulators of Protease-Activated Receptors with a Calcium Mobilization Assay Using a Plate Reader

Published on: May 24, 2024

Related Experiment Videos

Last Updated: May 12, 2026

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment
07:26

High-resolution Melting PCR for Complement Receptor 1 Length Polymorphism Genotyping: An Innovative Tool for Alzheimer's Disease Gene Susceptibility Assessment

Published on: July 18, 2017

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion
06:54

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion

Published on: June 15, 2019

Characterizing Modulators of Protease-Activated Receptors with a Calcium Mobilization Assay Using a Plate Reader
07:13

Characterizing Modulators of Protease-Activated Receptors with a Calcium Mobilization Assay Using a Plate Reader

Published on: May 24, 2024

Area of Science:

  • Immunology
  • Structural Biology
  • Biochemistry

Background:

  • The complement system is a crucial innate immune defense against pathogens.
  • Activation of complement Component 1 (C1) by antibodies leads to the generation of active C1s.
  • Active C1s cleaves complement Component 4 (C4), propagating the immune response.

Purpose of the Study:

  • To elucidate the structural and biochemical mechanisms controlling the interaction between C1s and C4.
  • To understand how C1s transitions from an inactive zymogen to an active protease capable of binding C4.

Main Methods:

  • Surface plasmon resonance was used to assess C1s binding to C4.
  • Crystal structure determination of a zymogen C1s construct (including CCP and SP domains).

Main Results:

  • Zymogen-to-active C1s transition is essential for C4 binding.
  • Crystal structure reveals inhibitory loop conformations in zymogen C1s.
  • Active C1s repositions loops for interaction with C4 sulfotyrosine residues.
  • The CCP1-CCP2 domain junction reveals a C4 binding exosite.

Conclusions:

  • A structural basis for C1s-C4 interaction control is provided.
  • Findings offer insights into therapeutic strategies for modulating complement activation.