The structure and function of vertebrate mannose lectin-like proteins

Area of Science:

• Immunology
• Glycobiology

Background:

• Sugar-specific recognition is vital for cell interactions and host defense.
• Macrophages express lectin-like proteins for recognizing specific sugars like mannose.
• Terminal mannose is rare on mammalian cells but common on lower organisms.

Purpose of the Study:

• To review mannose recognition systems in mammals.
• To explore the roles of the mannose receptor and mannose-binding protein in host defense.

Main Methods:

• Focus on the mannose receptor on macrophages and mannose-binding protein in plasma.
• Discuss receptor binding characteristics, pH dependency, and cellular recycling.
• Describe the structure and regulation of mannose-binding protein.

Main Results:

• The mannose receptor binds high-mannose glycoproteins at neutral pH and recycles rapidly.
• Mannose receptor expression is regulated, increasing in macrophages and modulated by cytokines.
• Mannose-binding protein, an acute phase reactant, shows homology to surfactant proteins and may aid pathogen recognition.

Conclusions:

• The mannose receptor and mannose-binding protein likely cooperate to combat mannose-expressing infectious agents.
• These systems represent key mammalian mechanisms for recognizing and defending against pathogens with specific sugar structures.