Abstract
Psoralens in combination with ultraviolet light are potent modulators of epidermal cell growth and differentiation. Responsive cell types contain specific, saturable, high-affinity binding sites for the psoralens. These binding sites become covalently modified by the psoralen molecule following ultraviolet light exposure. In the present studies the psoralen receptor, labeled with [3H]8-methoxypsoralen, was visualized in the cytoplasmic and plasma membrane fractions of HeLa cells following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The receptor had an apparent molecular mass of approximately 22,000 daltons and was shown to be sensitive to protease, but not nuclease treatment. The radiolabeled receptor could not be visualized in nuclear extracts of cells. Covalent binding of the radioligand to the receptor protein was inhibited by excess unlabeled 8-methoxypsoralen, indicating that covalent psoralen-receptor binding was saturable. In addition, the covalently modified receptor was found to persist in cells for over 5 h. The presence of a cellular protein that exhibits specific affinity for the psoralens and becomes photoalkylated by these compounds, together with previous data showing that the psoralens have direct effects on the cell surface membranes, supports our model that some of the biological effects of photoactivated psoralens are receptor-mediated.
Highlights
University of Medicine and Dentistry of New Jersey, Piscatawuy, New Jersey 08854 range, requires UVA light, and is observed immediately following psoralens and UVA light (PUVA) treatment.Althoughtheprecisemechanism underlying the inhibition of EGF binding is not known, we Psoralens in combination with ultraviolet light are have shown that PUVA treatment inhibits internalizationof potent modulatorsof epidermal cell growth and differ- the EGF-receptor complex, but not metabolismof EGF once entiation
These binding sites become covalently modified by the phospholipid-dependent protein kinase, protein kinaseC, the psoralen molecule following ultraviolet light exposure
We describe the partial puriof the radioligand to the receptor protein was inhibited fication of the psoralen receptor from HeLa cell membrane by excess unlabeled 8-methoxypsoralen, indicating and cytoplasmic subcellular fractionTsh. e receptor was found that covalent psoralen-receptorbinding was saturable. to be a protein having a molecularmass of approximately
Summary
Mammalian cells contain receptor sites for the psoraletnhsat are distinct from DNA [3, 4].Binding of psoralens to these receptors is both saturable and reversible. After 10 min in the homogenization buffer, the cellular material was removed from the plates by gentle pipetting This treatment solubilized cytoplasm and plasma membrane while the nuclei remained intact [8].The extent. The abbreviations used are: UVA light, ultraviolet light of wave- supernatant,containing soluble plasma membrane and cytoplasm, length 320-400 nm; PUVA, psoralens used in combination with UVA was decanted and the remaining nuclear pellet was sonicated on ice light; EGF, epidermal growth factor; SDS, sodium dodecyl sulfate.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
