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Lecture 2

GENE 500 Lecture Notes - Lecture 2: Coiled Coil, Leucine Zipper, Structural Motif

Course Code
GENE 500
Lawrence Grossman

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Lecture 2 - Structure Motifs
A particular combination of two or more secondary structures that form a distinct three-
dimensional structure is called a structural motif when it appears in multiple proteins
Structural motif is associated with a specific function (most of the time)
Example: Coiled-coil Many proteins, including fibrous proteins and DNA-regulating
proteins called transcription factors, assemble into dimers or trimers by using a coiled-
coil motif, in which α helices from two, three, or even four separate polypeptide chains
coil about one anotherresulting in a coil of coils; the example shown above is held
together by non-polar residues at 1 & 4th position of the repeating 7 heptad amino acid
units) Leucine zipper (hydrophobic interactions)
EFHand/Helix-Loop-Helix Motif: The binding of a Ca2+ ion to oxygen atoms in
conserved residues in the loop depends on the concentration of Ca2+ in the cell and
sometimes induces a conformational change in the protein, altering its activity
Calcium concentration directly controls protein’s structure and functions; similarly,
some structural motifs are used for protein binding to DNA and, consequently, for the
regulation of gene activity
In calcium-binding proteins such as calmodulin, oxygen atoms from five residues in the
acidic glutamate- and aspartate-rich loop and one water molecule form ionic bonds with
a Ca2+ ion
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