1n9d: Difference between revisions
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'''SOLUTION STRUCTURE OF HUMAN PROLACTIN''' | '''SOLUTION STRUCTURE OF HUMAN PROLACTIN''' | ||
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[[Category: Hodsdon, M E.]] | [[Category: Hodsdon, M E.]] | ||
[[Category: Keeler, C.]] | [[Category: Keeler, C.]] | ||
[[Category: | [[Category: Four alpha-helical bundle]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:15:27 2008'' | |||
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Revision as of 02:15, 3 May 2008
SOLUTION STRUCTURE OF HUMAN PROLACTIN
OverviewOverview
Human prolactin is a 199-residue (23 kDa) protein closely related to growth hormone and placental lactogen with properties and functions resembling both a hormone and a cytokine. As a traditional hormone, prolactin is produced by lactotrophic cells in the pituitary and secreted into the bloodstream where it acts distally to regulate reproduction and promote lactation. Pituitary cells store prolactin in secretory granules organized around large prolactin aggregates, which are produced within the trans layer of the Golgi complex. Extrapituitary prolactin is synthesized by a wide variety of cells but is not stored in secretory granules. Extrapituitary prolactin displays immunomodulatory activities and acts as a growth factor for cancers of the breast, prostate and tissues of the female reproductive system. We have determined the tertiary structure of human prolactin using three-dimensional (3D) and four-dimensional (4D) heteronuclear NMR spectroscopy. As expected, prolactin adopts an "up-up-down-down" four-helical bundle topology and resembles other members of the family of hematopoietic cytokines. Prolactin displays three discrete structural differences from growth hormone: (1) a structured N-terminal loop in contact with the first helix, (2) a missing mini-helix in the loop between the first and second helices, and (3) a shorter loop between the second and third helices lacking the perpendicular mini-helix observed in growth hormone. Residues necessary for functional binding to the prolactin receptor are clustered on the prolactin surface in a position similar to growth hormone. The backbone dynamics of prolactin were investigated by analysis of 15N NMR relaxation phenomena and demonstrated a rigid four-helical bundle with relatively mobile interconnecting loops. Comparison of global macromolecular tumbling at 0.1mM and 1.0mM prolactin revealed reversible oligomerization, which was correlated to dynamic light scattering experiments. The existence of a reversible oligomerization reaction in solution provides insight into previous results describing the in vitro and in vivo aggregation properties of human prolactin.
About this StructureAbout this Structure
1N9D is a Single protein structure of sequence from Homo sapiens. The following page contains interesting information on the relation of 1N9D with [Growth Hormone]. Full crystallographic information is available from OCA.
ReferenceReference
The tertiary structure and backbone dynamics of human prolactin., Keeler C, Dannies PS, Hodsdon ME, J Mol Biol. 2003 May 16;328(5):1105-21. PMID:12729745 Page seeded by OCA on Sat May 3 02:15:27 2008