Complement System | Classical Pathway

Share this & earn $10
Hussain Biology
Published at : 06 Dec 2020
29242 views
1035
14

The complement system is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen's cell membrane. It is part of the innate immune system, which is not adaptable and does not change during an individual's lifetime. The complement system can, however, be recruited and brought into action by antibodies generated by the adaptive immune system.
The complement system consists of a number of small proteins that are synthesized by the liver, and circulate in the blood as inactive precursors. When stimulated by one of several triggers, proteases in the system cleave specific proteins to release cytokines and initiate an amplifying cascade of further cleavages.
Most of the proteins and glycoproteins that constitute the complement system are synthesized by hepatocytes. But significant amounts are also produced by tissue macrophages, blood monocytes, and epithelial cells of the genitourinary system and gastrointestinal tract. The three pathways of activation all generate homologous variants of the protease C3-convertase. The classical complement pathway typically requires antigen-antibody complexes for activation (specific immune response), whereas the alternative pathway can be activated by spontaneous complement component 3 (C3) hydrolysis, foreign material, pathogens, or damaged cells. The mannose-binding lectin pathway can be activated by C3 hydrolysis or antigens without the presence of antibodies (non-specific immune response). In all three pathways, C3-convertase cleaves and activates component C3, creating C3a and C3b, and causes a cascade of further cleavage and activation events. C3b binds to the surface of pathogens, leading to greater internalization by phagocytic cells by opsonization.

The classical pathway is triggered by activation of the C1-complex. The C1-complex is composed of 1 molecule of C1q, 2 molecules of C1r and 2 molecules of C1s, or C1qr2s2. This occurs when C1q binds to IgM or IgG complexed with antigens. A single pentameric IgM can initiate the pathway, while several, ideally six, IgGs are needed. This also occurs when C1q binds directly to the surface of the pathogen. Such binding leads to conformational changes in the C1q molecule, which leads to the activation of two C1r molecules. C1r is a serine protease. They then cleave C1s (another serine protease). The C1r2s2 component now splits C4 and then C2, producing C4a, C4b, C2a, and C2b (historically, the larger fragment of C2 was called C2a but is now referred to as C2b). C4b and C2b bind to form the classical pathway C3-convertase (C4b2b complex), which promotes cleavage of C3 into C3a and C3b. C3b later joins with C4b2b to make C5 convertase (C4b2b3b complex).
complement systemcomplement pathwayclassical pathway of complement system

Insolvency vs. Default vs. Bankruptcy: Three Terms Defined, Explained and Compared in One Minute

Insolvency vs. Default vs. Bankruptcy: Three Terms Defined, Explained and Compared in One Minute

Mark Lanegan Band - Stitch It Up

Mark Lanegan Band - Stitch It Up

Liam Payne - Depend On It (Lyrics)

Liam Payne - Depend On It (Lyrics)

7 Simple Life Hack For Easier Your Life

7 Simple Life Hack For Easier Your Life

Trying Wild Celebrity Breakfast Foods | People Vs. Food

Trying Wild Celebrity Breakfast Foods | People Vs. Food

Zoho Books Accounting Software Review / Tutorial - Part 1

Zoho Books Accounting Software Review / Tutorial - Part 1

Steven Universe Future Official Soundtrack | Looking Forward (feat. Kate Micucci) | Cartoon Network

Steven Universe Future Official Soundtrack | Looking Forward (feat. Kate Micucci) | Cartoon Network

TYPICAL TYPICALLY | USAGE | EXPLAINED IN TAMIL

TYPICAL TYPICALLY | USAGE | EXPLAINED IN TAMIL

Fix "Windows Could not Automatically Detect Network’s Proxy Settings"

Fix "Windows Could not Automatically Detect Network’s Proxy Settings"

Sade - By Your Side (Official Video)

Sade - By Your Side (Official Video)

Documentary filmed inside VRChat: A Wider Screen

Documentary filmed inside VRChat: A Wider Screen

Louis: "Some people genuinely think that we're in a relationship"

Louis: "Some people genuinely think that we're in a relationship"

The right [ WA] - Biggest ever?

The right [ WA] - Biggest ever?

New Christmas Wreath & Best New Purchase? | VLOGMAS

New Christmas Wreath & Best New Purchase? | VLOGMAS

How to Tie the Celtic Heart Knot by TIAT (A Knotty Valentine)

How to Tie the Celtic Heart Knot by TIAT (A Knotty Valentine)

Model Aircraft: How to Install a Canopy

Model Aircraft: How to Install a Canopy

Preview: Anne Klinge sweeps the Judges off their feet

Preview: Anne Klinge sweeps the Judges off their feet

HOT TAKE: Q4 could prove to be the most difficult quarter of 2020 and that is not Good

HOT TAKE: Q4 could prove to be the most difficult quarter of 2020 and that is not Good

voiced and unvoiced consonants

voiced and unvoiced consonants

Palms - Future Warrior [Official Music Video]

Palms - Future Warrior [Official Music Video]

[MV] ROTHY (로시) - Rainbow (레인보우) | Romance is A Bonus Book OST Part. 2 (로맨스는 별책부록)

[MV] ROTHY (로시) - Rainbow (레인보우) | Romance is A Bonus Book OST Part. 2 (로맨스는 별책부록)

Atlas Genius - If So (Lyrics)

Atlas Genius - If So (Lyrics)

Dwelling Places

Dwelling Places

saruta-ma pentru ultima oara

saruta-ma pentru ultima oara

Moro - LI LIHA LIHA Feat PROFIT ZA3IM ( SKIZOBEAT )

Moro - LI LIHA LIHA Feat PROFIT ZA3IM ( SKIZOBEAT )

Repsol Honda Team look ahead to the #ValenciaGP

Repsol Honda Team look ahead to the #ValenciaGP

Top Tips for Maintaining your Car - Honda UK

Top Tips for Maintaining your Car - Honda UK

DEAMN - Sign (Audio)

DEAMN - Sign (Audio)

| TURNS ON POINTE |

| TURNS ON POINTE |

Mianite Is (Mostly) Back

Mianite Is (Mostly) Back

Modern Talking Cheri Cheri Lady Mr  Stephen Remix  2018 RETRO SENSATION

Modern Talking Cheri Cheri Lady Mr Stephen Remix 2018 RETRO SENSATION

Self Love Shifts that Changed My Life 💕

Self Love Shifts that Changed My Life 💕

10cm - Condition (demo) / 미발매곡

10cm - Condition (demo) / 미발매곡

Vir The Robot Boy - Mad Max trying to stops the train

Vir The Robot Boy - Mad Max trying to stops the train

You Only Pink Twice | The Pink Panther (1993)

You Only Pink Twice | The Pink Panther (1993)

Substantial - Ain't No Happy Ending

Substantial - Ain't No Happy Ending

Among Us Tips And Tricks-  How To Win As One Impostor- Impostor Gameplay

Among Us Tips And Tricks- How To Win As One Impostor- Impostor Gameplay

Zoho Books Overview | US Edition

Zoho Books Overview | US Edition

Animals are so funny that you can die of laughter - Funny animal compilation

Animals are so funny that you can die of laughter - Funny animal compilation

10 WOMAN KILLER fragrances for men....

10 WOMAN KILLER fragrances for men....

SICK INDIVIDUALS - SCARS ft. Cub Rayan (Official Lyric Video)

SICK INDIVIDUALS - SCARS ft. Cub Rayan (Official Lyric Video)

Understanding Accommodations

Understanding Accommodations

Genetics - The Transforming Principle - Lesson 12 | Don't Memorise

Genetics - The Transforming Principle - Lesson 12 | Don't Memorise

The Chase | Dialogue vs Demos: What's the better option?

The Chase | Dialogue vs Demos: What's the better option?

Round to the nearest ten, whole number, tenth or hundredth

Round to the nearest ten, whole number, tenth or hundredth

Actual Fact, Relax

Actual Fact, Relax

ใช้คำไหนดี Definitely, Certainly, Of course, Alright, Sure | Tina Academy Ep.127

ใช้คำไหนดี Definitely, Certainly, Of course, Alright, Sure | Tina Academy Ep.127

"peace and tranquility  (meme?)

"peace and tranquility (meme?)

Genshin Impact Dancing | Specialist

Genshin Impact Dancing | Specialist