Answer
Complement proteins are a group of proteins that are part of the immune system's complement system. The complement system is a complex network of proteins that plays a critical role in immune defense, inflammation, and immune regulation. Complement proteins are produced by various cells in the body and are named based on a systematic numbering system.
**Source of Complement Proteins:**
Complement proteins are synthesized by various cells, including liver cells (hepatocytes) and immune cells such as macrophages, dendritic cells, and neutrophils. Some complement proteins are produced as inactive precursor forms, which are activated during the complement cascade in response to the presence of pathogens.
**Naming of Complement Proteins:**
Complement proteins are named with a letter "C" followed by a number that corresponds to their order of discovery or characterization. The complement system consists of more than 30 proteins, and they are typically referred to using their complement protein number (C1, C2, C3, etc.). Some key complement proteins include:
1. **C1, C2, C3, C4:** These are the initial components of the classical pathway of the complement system. C1 consists of three subcomponents (C1q, C1r, and C1s) and is activated by binding to antigen-antibody complexes, triggering a cascade of reactions involving C2 and C4 that leads to the formation of the C3 convertase.
2. **C5-C9:** These proteins are involved in the later stages of the complement cascade and are responsible for the formation of the membrane attack complex (MAC). The MAC creates pores in the membranes of target cells, leading to cell lysis and destruction.
3. **Factors B and D:** These proteins are involved in the alternative pathway of the complement system. Factor B is activated by factors produced during infections, and factor D cleaves it to form the alternative pathway C3 convertase, which is central to initiating complement activation in the absence of antibodies.
4. **Properdin (Factor P):** Properdin is a positive regulator of the alternative pathway. It stabilizes the C3 convertase, promoting continued complement activation.
5. **Regulatory Proteins (e.g., Factor H, Factor I, CD59):** These proteins play a critical role in preventing excessive complement activation on host cells. They help ensure that the complement system targets pathogens while sparing healthy cells.
The naming convention allows researchers and immunologists to systematically refer to and understand the roles of these proteins within the complement system. Overall, complement proteins are essential for coordinating various immune responses, enhancing phagocytosis, promoting inflammation, and facilitating the removal of pathogens and damaged cells.
Work Step by Step
Complement proteins are a group of proteins that are part of the immune system's complement system. The complement system is a complex network of proteins that plays a critical role in immune defense, inflammation, and immune regulation. Complement proteins are produced by various cells in the body and are named based on a systematic numbering system.
**Source of Complement Proteins:**
Complement proteins are synthesized by various cells, including liver cells (hepatocytes) and immune cells such as macrophages, dendritic cells, and neutrophils. Some complement proteins are produced as inactive precursor forms, which are activated during the complement cascade in response to the presence of pathogens.
**Naming of Complement Proteins:**
Complement proteins are named with a letter "C" followed by a number that corresponds to their order of discovery or characterization. The complement system consists of more than 30 proteins, and they are typically referred to using their complement protein number (C1, C2, C3, etc.). Some key complement proteins include:
1. **C1, C2, C3, C4:** These are the initial components of the classical pathway of the complement system. C1 consists of three subcomponents (C1q, C1r, and C1s) and is activated by binding to antigen-antibody complexes, triggering a cascade of reactions involving C2 and C4 that leads to the formation of the C3 convertase.
2. **C5-C9:** These proteins are involved in the later stages of the complement cascade and are responsible for the formation of the membrane attack complex (MAC). The MAC creates pores in the membranes of target cells, leading to cell lysis and destruction.
3. **Factors B and D:** These proteins are involved in the alternative pathway of the complement system. Factor B is activated by factors produced during infections, and factor D cleaves it to form the alternative pathway C3 convertase, which is central to initiating complement activation in the absence of antibodies.
4. **Properdin (Factor P):** Properdin is a positive regulator of the alternative pathway. It stabilizes the C3 convertase, promoting continued complement activation.
5. **Regulatory Proteins (e.g., Factor H, Factor I, CD59):** These proteins play a critical role in preventing excessive complement activation on host cells. They help ensure that the complement system targets pathogens while sparing healthy cells.
The naming convention allows researchers and immunologists to systematically refer to and understand the roles of these proteins within the complement system. Overall, complement proteins are essential for coordinating various immune responses, enhancing phagocytosis, promoting inflammation, and facilitating the removal of pathogens and damaged cells.
