Membrane Lipids & Bile Acid Metabolism Flashcards
Major Phospholipids & Characteristics
Phosphatidylcholine (lecithin)
Phosphatidylserine
Phosphatidylethanolamine
Phsophatidylinositol
- all contain FA
- phosphoglycerides & sphingolipids syn in all body tissues on ER except erythrocytes
- Enzymes present in cytoplasm or associated w/ ER mem
Phsopholipid Structure
Phospholipid Syn
Phosphatidylcholine Syn from phosphatidylserine
SAM very important methyl group donor
Salvage Pathway
Phosphatidylcholine can by synthesized from dietary choline when available.
If not available, PC can be made from glycolytic producs but isn’t suffiicient to prevent choline def
Cardiolipin
found in inner mitoch mem where maintains certain resp complexes on ETC
Only human glycerophospholipid that is antigenic
Can be recognized by Y against trepanoma pallidum (syphalis)
Autoimmune disease
Dipalmitoylphosphatidylcholine
Major part of lung surfactant
Made & secreted by granular pneumocytes
Lung surfatant lines alveoli
Decreases surface T of fluid layer reducing P needed to reinflat alveoli preventing collapse
Respiratory Distress Syndrome
Prevalent in premature infants
Due to def in syn of lung surfactant
Major constituents of surfactant are dipalmitoylphosphatidylcholine, phosphatidylglycerol, apoproteins (Sp A, B, C) & cholesterol
Measure: DPPC/S ratio 2:1 maturity
Platelet Activating Factor
present @ low [] but EXTREMELY potent!
Hormone released from phagocytic cells binds to surface proteins.
Causes platelets to aggregate & degranulate. It binds to surface R resulting in thrombotic & inflammatory events & anaphylactic rxns.
Causes neutrophils & alveoli macrophages to produce superoxide radicals
Plasmalogen (ethanolamine)
Phosphatidalethanolamine (in nerves)
Phosphatidalocholine (abundant in heart m.)
Found w/in peroxisomes
Plasmalogens 2
Plasmalogen def plays important role in Alzheimer’s disease pathogenesis, particularly in white matter, & suggested that altered plasmalogen content contributes to neurodegen & synapse loss.
Syn of plasmalogens occur w/in peroxisomes & in patients w/ Zellweger syndrome- little to no syn which results in death at an early age if it’s severe
F not well known. Resistance to phsopholipases?
Phospholipases
Degradation & remodeling of phospholipids
Present in cell mem & lysosomes of all tissues & pancreatic secretions
*not in humans
Phospholipase actions
Phospholipase 2
Glycosphingolipids
Intracell communication
Found on outer leaflet of PM where they interact w/ extracell environment
Play a role in regulation of cell interactions, growth & dev
Act as antigenic determinants of ABO blood group & also source of various embryonic antigesns important in particular stages of fetal dev
Essential components of all cell mem but found in nerve tissue
Some are antigenic
Tay Sachs
auto recessive
Hexoaminidase A def
GM2 ganglioside in nerve cells accumulates
Mental retardation, blindness, m. weakness, seizures, cherry-red macula, early mortality
infantile/juvenile/adult
Guacher disease
auto recessive
Glucoceribrosidase def
Glucocerebroside accum in spleen, liver, lungs, bone marrow & brain
Hepatosplenomegaly
mental retardation in type 2 & 3
skeletal disorder in type 1
Use enz replacement therapy
Fabry
x linked
a galactosidase A def
Globosides accum in eyes, kidneys, ANS & cardiovascular sys
Kidney failure, heart failure or stroke, reddish purple skin rashes, burning sensation in hands
use enz replacement
Niemann Pick disease
Auto recessive
Sphingomyelinase def
Sphingomyelin accum in spleen, liver, lungs, bone marrow & brain
Type A- jaundice, hepatomegaly, profound brain damage (infantile)
Type B- large liver & spleen (teens)
Type C/D- moderate enlargement of spleen & liver, extensive brain damage (adult)
Bone marrow transplant
Krabbes disease
Auto rec
B galactosidase def
Galactocerebroside accum. Globids cells, breakdown myelin in nerve, destruction of brain cells
Mental, motor deterioration, irritability, fever, seizures, vomiting, feeding difficulty, m. weakness, deafness, blindness
Sandhoff Disease
Auto Rec
Hexosaminidase A & B def
GM2 & globosides accum in brain & other organs
Severe form of Tay Sachs, motor weakness, early blindness, macrocephaly, cherry red spot in eye, seizures infantile
Metachromatic leukodystrophy MLD
auto recessive
Arylsulfatase A def
Sulfatides accum in nervous sys, liver, kidney
Difficulty walking, m. wasting & weakenss, blindess, convulstions, impaired swallowing, paralysis, dementia (infantile) dementia, (juvenile) psychiatric disorder (adult)
Farber Disease
auto recessive
Ceraminidase def
Ceramid accum in joints, CNS, liver, heart, kidney
Impaired motor & mental ability, difficulty swallowing, arthritis, swollen LN & joints, horesness (infantile)
Sphingolipidoses
- measure enz activity in cultured periph leukocytes or macrophages
- histological exam of tissues: tay sach’s shell like inclusions; Gaucher inclusions more like wrinkeled paper
- DNA analysis (southern blotting)
- prenatal diagnosis using amniocytes or chorionic villi
