Endomembrane System
2018-06-04 08:44:33 5 举报AI智能生成
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Endomembrane System
Golgi complexes
morpholoy
disklike membranous cisternae
dilated rim
cis(forming) face & trans(secreting) face
glycosylation
N-linked oligosaccharide modifications
attachment of N-acetylgalactosamine to Ser or Thr
cis-Golgi
removal of mannose
medial cisternae
addition of galactose
addition of sialic acid
trans-Golgi
O-linked oligosaccharide modifications
trans-Golgi (less common)
functions
aid folding and transport
resistant to digestion by protease
regulatory roles in signaling
secretion
constitutive secretion
regulated secretion
vesicular transport
vesicular transport model
cisternal maturation model
Lysosomes
high concentration of hydrolytic enzymes
pH 4.5
marker enzyme: acid phosphatase
primary lysosomes
second lysosomes
residual body
heterogenous organelle
biogenesis
from Golgi appratus
Mannose-6-phophate to indicate proteins to lysosomes
signal patch to indicate mannose phosphorylation
phagocytosis（吞噬）
autophagy（自噬）
endocytosis（胞吞）
LDL digestion by recepor mediated endocytosis（受体介导的胞吞）
related diseases
Silicosis （矽肺）
inclusion-cell disease（细胞内含物病）
神经节苷脂储集症
vacuoles
related to animal cell lysosomes
storage of nutrients and waste products
increase cell size
control osmotic pressure
Peroxisomes
originate from ER or peroxisomes division
Features
mitocondria and chloroplasts are not included
only in eukaryotic cells
Endoplasmic Reticulum (ER)
Rough ER
more than half of the total membrane (in animals)
tubules and flattened sacs
continuous with outer nuclear membrane
the space inside: lumen or cisternal space
ribosomes on it has no differences with those in cytosol
protein synthesis
products
secretory proteins
integral membrane proteins
half of eukaryotic proteins
N-linked to Asn
by oligosaccharyl tranferase which bound to the membrane
linked to protein translocator（移位蛋白）
oligosaccharide is linked to dolichol（多萜醇）
synthesized outside then filped inside
formation of disulfide bonds
by protein dislfide isomerase (PDI)
quality control of new proteins
chaperones
calnexin（钙联接蛋白）
clareticulin（钙网蛋白）
PDI
GT (glucosyl tranferase，葡糖基转移酶)
ER stress
synthesis of membrane lipids
most lipids are synthesized entirely within ER
except
sphingomyelin
glycolipids
unique lipids in Mit or Chl
asymmetric synthesis
scramblase（混杂酶）
ER
non-specific
flippase（翻转酶）
plasma mambrane
specific
Smooth ER
steroid synthesis
detoxification
Release of glucose 6-phosphate in liver cells
Sequestration of Ca2+
nuclear envelope
Cytoplasmic matrix（细胞质基质）
Alias
Cytosol（胞质溶胶）
Definition
Functions
the place of metabolism
Glycolysis
PPP
Gylcongenesis
maintain cell morphology with cytoskeleton
proteins
modification
covalent connection of coenzymes or cofactors
phosphorylation or dephosphorylation
methylation
acetylation
repair
renaturation of denaturated or misfolded protein
a heat-shock response is triggered to stimulate the expression of chaperones
synthesis
degradation
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