Human growth hormone: Difference between revisions
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==Structure== | ==Structure== | ||
'''Primary Sequence'''<br/> | |||
hGH is produced within the cell as a pre-protein, consisting of a 191 polypeptide chain associated with a 26 amino acid signal peptide. This signal peptide functions in membrane translocation, and is eventually cleaved to yield the mature form of hGH-1. The signal peptide is cleaved from the 191 polypeptide chain of hGH-1 by an ER membrane-bound protease (Chawla, Parks, and Rudman, 1983) | hGH is produced within the cell as a pre-protein, consisting of a 191 polypeptide chain associated with a 26 amino acid signal peptide. This signal peptide functions in membrane translocation, and is eventually cleaved to yield the mature form of hGH-1. The signal peptide is cleaved from the 191 polypeptide chain of hGH-1 by an ER membrane-bound protease (Chawla, Parks, and Rudman, 1983) | ||
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Isoform 4: excludes amino acid residues 117-162 | Isoform 4: excludes amino acid residues 117-162 | ||
'''Secondary Structure'''<br/> | |||
hGH is a single chain peptide, which was 45% helical with 8 α-helices (Chantalat et al., 1995). Protein Data Bank (PDB) provides predicted secondary structures of different proteins using the research from the paper and an algorithm program. | hGH is a single chain peptide, which was 45% helical with 8 α-helices (Chantalat et al., 1995). Protein Data Bank (PDB) provides predicted secondary structures of different proteins using the research from the paper and an algorithm program. | ||
'''Tertiary Structure'''<br/> | |||
The known crystal structure of hGH illustrate that the core of the protein is a four-helix bundle. Helices 1 & 4 at the NH2 and COOH ends are longer than helices 2 & 3 (Abraham 1992). A short loop connects helices 2 & 3 and two long crossover connections link helices 1 & 2 and helices 3 & 4. The helices run up-up-down-down (Abraham 1992). This is unusually because normally four helix bundles exhibit up-down-up-down orientation. | The known crystal structure of hGH illustrate that the core of the protein is a four-helix bundle. Helices 1 & 4 at the NH2 and COOH ends are longer than helices 2 & 3 (Abraham 1992). A short loop connects helices 2 & 3 and two long crossover connections link helices 1 & 2 and helices 3 & 4. The helices run up-up-down-down (Abraham 1992). This is unusually because normally four helix bundles exhibit up-down-up-down orientation. | ||