LS3protein_function

LS3protein_function - Function of proteins -most work in...

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Function of proteins -most work in the cell are done by proteins, how do proteins work? 1. Protein family Why different proteins have different functions? 2. How do proteins work? -antibodies -enzymes 3. How are proteins regulated in the cell
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-Proteins with similar sequence often have the similar structure and similar function -Proteins with the similar structure/function are grouped together as protein families, members of the same protein family are usually evolutionarily related -Different types of proteins: antibodies, enzymes, transcription factors, structural proteins, Transport proteins ... 1. Protein family
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Members of a protein family have similar amino acid sequences Myoglobin hemolobin
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Members of a protein family have similar structure and function 16 kD Single peptide protein Muscle O 2 carrier 64 kD 4-subunit protein blood O 2 carrier
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2. How proteins work? -Proteins work by binding to other molecules, called ligands or substrates, including small ones such as ions or sugars, and large ones such as proteins, DNA, and RNA. -The protein-ligand interaction can be transient, stable, or permanent, but they are all specific -Protein function can be measured by its interaction with a ligand: affinity refers to the binding strength (measured by Kd), specificity refers to substrate preference
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Animals produce antibodies or immunoglobulins (Ig) in response to foreign molecules, small or large. Antibodies are highly specific, they can distinguish proteins that differ by only a single amino acid. Antibody-inducing agents are called antigens. The region of an antigen recognized by an antibody is called epitope. Antibodies bind tightly to specific antigens with > 10-9 M affinity. Protein works by specifically binding to other molecules e.g. Antibodies
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Antibodies or Immunoglobulins 1. antibody has 4 subunits An antibody molecule contains 4 polypeptide chains, two heavy chains (H), and two light chains (L), The variable domains contains the complementarity-determining region (CDR), which interacts with the antigen, whereas the constant domains allow each antibody to have similar structures. Each polypeptide chain can be divided into two domains, a variable domain (VL and VH), different in different antibody, and a constant domain, same in different antibody.
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Pathogens Bloodstream Bloodstream Bacteria Viruses Fungi infection Approximately 1 million B cells, each with a different antibody on  the cell surface. A small fraction will  be capable of binding pathogen 
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This note was uploaded on 03/14/2012 for the course LS 3 taught by Professor Lin during the Fall '06 term at UCLA.

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LS3protein_function - Function of proteins -most work in...

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