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The mechanism of lactogen receptor binding by human prolactin

Sivaprasad, Umasundari
http://rave.ohiolink.edu/etdc/view?acc_num=osu1054499303

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Ohio State Biochemistry Program.
Communication between multiple binding sites in a macromolecule has been demonstrated to occur through conformation changes propagated through regions of the molecules that do not constitute the binding interfaces. This work has examined whether two receptor-binding sites on a hormone are functionally coupled. Prolactin, a lactogenic hormone, binds to two prolactin receptors in a sequential manner, the first receptor binding at Site 1 of the hormone followed by the second receptor binding at Site 2. The detailed mechanics of receptor binding however are unclear. In the work presented here, the mechanism by which the extracellular domain of the human prolactin receptor binds to human prolactin has been investigated using surface plasmon resonance technology where prolactin is coupled to a dextran surface using bulky coupling chemistries that reside in, and block either Site 1 or Site 2. When the receptor is passed over the protein with Site 2 blocked by the coupling linkage, the receptor binds to the hormone, indicating that Site 1 function is independent of Site 2. However, if Site 1 is blocked by the coupling linkage, no receptor binding can be measured, suggesting that receptor binding at Site 2 is dependent on receptor occupancy of Site 1. Kinetic analysis of binding site mutants has supported this hypothesis since corruption of Site 1 dramatically reduces the amount of receptor bound to the hormone. Using site-directed mutagenesis, a set of hydrophobic residues in hPRL has been identified, whose mutation reduces the Site 2 activity of hPRL and is proposed to transmit a conformational change initiated by Site 1 binding to organize and create a functional chemical geometry within Site 2. We propose that binding of one receptor to hPRL induces a conformation change in the hormone, which is transmitted by the hydrophobic residues and activates the second receptor-binding site.
Charles Brooks (Advisor)
Chemistry, Biochemistry
prolactin; prolactin receptor; binding kinetics; hydrophobic residues; conformation change

Recommended Citations

Citations

  • Sivaprasad, U. (2003). The mechanism of lactogen receptor binding by human prolactin [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1054499303

    APA Style (7th edition)

  • Sivaprasad, Umasundari. The mechanism of lactogen receptor binding by human prolactin. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1054499303.

    MLA Style (8th edition)

  • Sivaprasad, Umasundari. "The mechanism of lactogen receptor binding by human prolactin." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1054499303

    Chicago Manual of Style (17th edition)

osu1054499303
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© 2003, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.