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Rough Endoplasmic Reticulum (RER) 
  • Structure 
    • composed of a lipid membrane with membrane bound ribosomes
    • lipid membrane is continuous with nuclear membrane
  • Function
    • synthesis of secretory proteins
      • e.g. peptide hormones
    • addition of N-linked oligosaccharides to peptides
  • Cell biology
    • RER is found in high concentration in
      • neurons
        • termed Nissl bodies
          • stain basophilic 
          • synthesize/secrete peptide neurotransmitters in prepackaged vesicles
      • pancreatic acinar cells
        • synthesize/secrete digestive enzymes
Smooth Endoplasmic Reticulum (SER)
  • Structure
    • lipid membrane without membrane bound ribosomes
  • Function 
    • steroid synthesis
    • detox of chemicals
      • makes compounds water soluble
      • two mechanisms
        • hydroxylation
          • via cytochrome P450 hydroxylase complex
        • conjugation
          • involves binding of polar moiety (e.g. glucuronate via glucuronyl transferase) to toxin
    • lipid metabolism
      • release of fatty acids from triglycerides
      • assembles lipoproteins for release
    • carbohydrate metabolism
      • gluconeogenesis
        • allows free glucose to be released into circulation during fasting by removing phosphate from glucose-6-phosphate
        • mediated by glucose-6-phosphatase
          • deficient in von Gierke's disease
            • glycogen storage disease type I
            • presentation
              • accumulation of glycogen in kidney and liver
                • hepatomegaly
              • hypoglycemia
  • Cell biology
    • found in high concentrations in
      • hepatocytes
      • kidney
      • adrenal cortex
      • corpus luteum
      • muscle
        • modified SER = sarcoplasmic reticulum
          • stores and releases calcium to mediate muscle contraction
 

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