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Transcript of Proteins
Four levels of protein structure
Like other immunoglobulins, IgE is produced by B cells and plasma cells and has only been found in mammals so far. The concentration of IgE in the circulation, though, is very low.
IgE is implicated in the immune system responses to most parasitic worms, and plays a role in the immune defense against certain protozoan parasites such as Plasmodium falciparum. It also plays a role in manifesting various allergic reactions.
Tau protein stabilizes microtubules through four tubulin binding domains (blue boxes) in case of the longest isoform. Binding of tau protein to the microtubules is maintained in equilibrium by coordinated actions of kinases and phosphatases.
Myoglobin is found in vertebrate muscle cells . When the muscle cells are put in action, they can quickly require a big amount of oxygen for respiration because of their incredible
demand for energy.
Therefore, muscle cells use myoglobin to accelerate oxygen diffusion and act as oxygen reserves for times of intense respiration.
Keratin is the key structural material making up the outer layer of human skin.
It is also the key structural component of hair and nails.
1. Titin is important in the contraction of striated muscle tissues.
2. The length is: 27,000 to 33,000 amino acids
3. Titin is the largest known protein.
4. Furthermore the gene for titin contains the largest number of exons.
5. Exons: The protein-coding region in the DNA.
Essential to blood coagulation
The main function of the insulin protein is to regulate the amount of glucose in the blood. It also regulates the formation of fatty acids in the liver.
The insulin molecule is made up of two polypeptide chains. These are connected by disulfide bridges. Insulin has a quaternary structure. All in all it consists of 51 amino acids.
Collagen is a protein made up of amino-acids (Glycine, Proline, Hydroxyproline and Arginine), which are in turn are all built of carbon, oxygen and hydrogen.
It is the main part of tissues such as ligaments and muscles, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content.
the worker molecules of living organisms
Primary structure is the
of amino acids.
There are 20 different amino acids.
between amino acids.
Secondary structure is regular patterns of folding and twisting of the polypeptide.
beta pleated sheets
They are stabilized by hydrogen bonds.
Tertiary structure is further folding of the polypeptide.
It is stabilized by interactions between the side chains (R groups) of the amino acids.
Many types of bonds may be involved, including: ionic bonds, hydrogen bonds, Van der Waals interactions, and disulfide bonds.
Quaternary structure is the interaction of 2 or more polypeptides to form a protein.
Not all proteins have quaternary structure (some are made of just one polypeptide).
Quaternary structure is stabilized by the same types of bonding as in tertiary.
Allow facilitated diffusion of some molecules across the membrane.
Functions of membrane proteins
proteins sit on the surface of the membrane.
protein penetrate the membrane.
pumps for active transport
Energy is used to move molecules against a concentration gradient.
hormone binding sites
Enzymes embedded in membrane proteins complete the final stages of digestion.
cell to cell communication
A signaling pathway: the message is transferred from the receptor (1) to other proteins inside the cell. The proteins work together like runners in a relay race to carry the signal to its destination or destinations.
Membrane proteins are involved in cell adhesion, such as creating tight junctions between epithelial cells in the intestine.
Is the iron-containing oxygen-transport "metalloprotein" in the red blood cells of all vertebrates
consisting of about 6 percent heme and 94 percent globin
Myoglobin contains a heme prosthetic group (non-protein chemical compound) in the center around which the remaining Apo protein (protein part of an enzyme) folds. It has eight alpha helices and a hydrophobic core and is the primary oxygen-carrying pigment of muscle tissue.
T. VBH :3
Spectrin is a major structural protein in the nervous system of vertebrates and invertebrates. Multiple isoforms of spectrin are present within specialized plasma membrane subdomains of mammalian neurons.
The phosphorylation of tau (pink balls) regulates its activity to bind to microtubules and can affect axonal transport. Tau protein may inhibit the plus-end-directed transport of vesicles along microtubules by kinesin.
T VBH :3
Insulin is produced and stored in the body as a hexamer (a unit of six insulin molecules).
Within vertebrates, the amino acid sequence of insulin is strongly conserved.
It causes cells in the liver, skeletal muscles, and fat tissue to absorb glucose from the blood.
Insulin regulates carbohydrate and fat metabolism in the body.
The hexamer is far more stable than the monomer, which is desirable for practical reasons.
This means that insulin injections do not have to precede mealtimes by hours, which would give diabetics more flexibility in their daily schedules.
Insulin can aggregate and form fibrillar interdigitated beta-sheets. This can cause injection amyloidosis, and prevents the storage of insulin for long periods.
Fibrous keratin molecules supercoil to form a very stable, left-handed superhelical motif to multimerise, forming filaments consisting of multiple copies of the keratin monomer.
Limited interior space is the reason why the triple helix of the structural protein collagen, found in skin, cartilage and bone, has a high percentage of glycine.
- Mandal, Ananya. "Insulin Protein Structure." Insulin Protein Structure. News Medical, n.d. Web. 24 Sept. 2013.
- Holzwarth, Jonathan. " My Favorite Protein: Insulin." My Favorite Protein: Insulin. N.p., 17 Feb. 2010. Web. 24 Sept. 2013.
Spectrin is thought to stabilize the structure and composition of the plasma membrane at these sites. Mutations in spectrin are a cause of ataxia in humans and mice, and they affect the targeting and function of membrane channels.
Matrix-like retinal protein.
This protein is necessary to transer visual information from retinal photorecepters to bipolar cells.
long and narrow
usually insoluble in water
wide variety of functions
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