Nonenzymatic Protein Function and Protein Analysis Flashcards
Structural Proteins
generally fibrous
Include: collagen, elastin, keratin, actin, and tubulin
Motor Proteins
capable of force generation through a conformational change
Include: myosin, kinesin, and dynein
Binding Proteins
Bind a specific substrate, either to sequester it in the body or hold its concentration at steady state
Cell Adhesion Molecules (CAM)
bind cells to other cells or surfaces
Include: cadherins, integrins, and selectins
Antibodies (Immunoglobulins, Ig)
target a specific antigen, which may be a protein on the surface of a pathogen or a toxin
Collagen
makes up most of the extracellular matrix of connective tissue, strong and flexible (trihelical fiber)
Elastin
in extracellular matrix of connective tissue and primary role is to stretch and recoil
Keratins
intermediate filament proteins found in epithelial cells and they contribute to mechanical integrity of the cell
Actin
makes up microfilaments and the thin filaments in myofibrils, have a positive and negative side that allow motor proteins to unidirectionally travel
Tubulin
Makes up microtubules, which provide structure, chromosome separation in mitosis/meiosis, and intracellular transport
Myosin
primary motor protein that interacts with actin, it is the thick filament in a myofibril, its neck is responsible for the power stroke
Kinesin
key role in aligning chromosomes during metaphase and depolymerizing mircotubules in anaphase
bring vesicles towards the positive end of a microtubule
Dyenins
important in the movement of cilia and flagella
bring vesicles towards the negative end of a microtubule
Cadherins
groups of glycoproteins that mediate calcium depended cell adhesion
Integrins
group of proteins with two membrane spanning chains which are important in binding to and communicating with the extracellular matrix
Selectins
bind to carbohydrate molecules that project from other cell surfaces
Ion Channels
Permit facilitated diffusion of charges particles
Facilitated Diffusion
passive transport via diffusion down a concentration gradient through a pore created by a transmembrane protein
Ungated Channels
totally unregulated, always open
Voltage-Gated Channels
gate is regulated by the membrane potential change near the channel, closed under resting conditions
Ligand-Gated Channels
binding of a specific ligand to the channel causes it to open or close
Enzyme Linked Receptors
membrane receptors that display catalytic activity in response to ligand binding, three domains:
membrane spanning domain
ligand-binding domain
catalytic domain
G-Protein Coupled Receptors
Integral membrane proteins that are involved in signal transduction. Binding of ligand increases affinity of receptor for G protein and G protein binding switches it to an active state. Use a heterotrimeric G protein to transmit signals. They have an intracellular link to guanine nucleotides.
Electorphoresis
subjects compounds to an electric field, which moves them according to their net charge and size, negatively charges compounds migrate towards the positive anode and the positively charged compounds migrate towards the negative cathode
standard medium is polyacrylamide gel
Native PAGE
polyacrylamide gel electrophoresis (PAGE), is a method for analyzing proteins in their natural state, and is limited by the varying mass-to-charge and mass-to-size ratios of cellular proteins
most useful to compare size or charge
native protein can be recovered after
SDS-PAGE
completes PAGE and then adds SDS detergent to stain and visualize sections
useful to separate proteins based on mass alone
Isoelectric Focusing
Proteins are separated based on their isoelectric point
mixture is placed in a gel with a pH gradient (acidic anode, basic cathode) and an electric field is generated across the gel
Column Chromatography
column filled with silica or aluminum and gravity moves the solvent down the column
size and polarity separate the compounds
Ion-Exchange Chromatography
beads in column are coated in a charged substance to bind compounds of opposite charge
salt gradient used to elute charged molecules stuck to column
Size-Exclusion Chromatography
beads in column have pores of varying sizes that allow small compounds to enter and large compounds move through faster
Affinity Chromatography
customized column to bind with a specific substrate and is eluted by washing column with a free receptor for the protein
Protein Structure best assessed using
X-ray Crystallography and NMR spectroscopy
Amino Acid composition best assessed using
Complete protein hydrolysis and subsequent chromatographic analysis
Concentration best assessed using
Spectroscopy (often UV) or in an assay
