Proteins III Flashcards
catalyzes rxn of pyruvate lactate
Lactate dehydrogenase (LDH)
Protein isoform with two subunits:
M(muscle) and H(heart)
Higher than normal levels of H4 in the blood may suggest ______
myocardial infarction (heart attack)
Occurs via glycosyltransferases; it begins in the Endoplasmic reticulum and ends in the Golgi complex and is usually present on secreted protein such as TSH, LH, hCG, or membrane proteins.
Glycosylation of proteins
Function in proper folding of transmembrane proteins, structural stability, and recognition for cell adhesion.
Glycoproteins
Changes in HbA1c can be used to track effectiveness of
Diabetes treatment over the course of 4 months.
Protein acetylation promotes
resistance to degradation of proteins while in the cell.
Acetylation and Methylation contribute to the _______ and epigenetics which helps control gene expression in eukaryotes.
“Histone Code”
A way to anchor proteins to the cell membrane via acylation with myristoyl (C14) or palmitoyl (C16) groups; or prenylation with farnesyl (C15) or geranylgeranyl (C20) groups; or glycosylphosphatidylinositol (GPI) anchor.
Lipidation
Phosphorylation uses
kinases and phosphatases
Catalyzed by hydroxylases; seen in collagen and elastin
Hydroxylation
Requires vitamin K as a coenzyme; seen with glutamic acid in blood clotting factors. Resulting “Gla” proteins readily chelate Calcium.
Carboxylation
An erythrocyte (RBC) integral membrane protein.
Glycophorin
Can only be removed from the cellular membrane with detergents
Integral proteins
More loosely associated to the membrane
peripheral proteins
Three types of membrane transport proteins
Pumps, channels, transporters
Use energy released from ATP hydrolysis (ATP ADP +Pi) to move specific ions against an electrochemical gradient
Pumps
Allow the movement of ions down their electrochemical gradient (i.e passive transport).
Channels
Facilitate movement of specific small molecules or ions by going thru a conformational change.
Transporters
Transport down its concentration gradient
Uniporters
Move one molecule against its concentration gradient; while driving one or more ions down their concentration gradient.
Symporters and antiporters
The largest cell surface receptors
G protein coupled receptors
The major sorting center of the cell
Golgi complex
Protein path
Proteins travel from ribosomes (on rough ER) Golgi proper destination
Due to a series of hydrolytic enzymes being delivered to the wrong cell; as a result, there are high levels of these proteins in blood and urine and the lysosomes contain large inclusions of undigested glycosaminoglycans and glycolipids
I-cell disease (aka mucolipidosis II) Symptoms: psychomotor retardation and skeletal deformities Mechanism: Normally the enzymes contain mannose-6-phoshpate residue, but mannose-6-phoshate remains unphosphorylated and the enzyme is not able to direct hydrolytic enzymes from the Golgi to the lysosome.
N-linked or O-linked ______ of AA with distal amino (Arg, Lys) or carboxyl (Asp, Glu) groups. Amino groups may be mono-, di-, or tri-substituted.
methylation
Membranes vary in protein content: myelin sheath ____%; plasma membrane____%; mitochondrial membrane _____%
18; 50; 75
TM proteins have three parts:
extracellular, membrane-spanning, and cytoplasmic
Thermal and chemical (except ____) denaturation usually reversible
SDS
