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Platelet glycoproteins IIb and IIIa as a calcium channel in liposomes
| Content Provider | Scilit |
|---|---|
| Author | Rybak, Me Renzulli, La Bruns, Mj Cahaly, Dp |
| Copyright Year | 1988 |
| Description | Human platelet membrane glycoproteins IIb and IIIa (GPIIb and IIIa) were incorporated into phospholipid vesicles by the reverse-phase technique to assess the ability of GPIIb and IIIa to function as a Ca2+ channel. Movement of Ca2+ across the lipid bilayer was quantitated by injection of proteoliposomes with encapsulated Fura-2 into Ca2+ buffers and measurement of Fura-2 fluorescence as an indicator of Ca2+ influx. Reciprocally, to assess the function of proteins in an inside-out orientation, Ca2+-loaded vesicles were injected into Ca2+-free buffer and Ca2+ efflux monitored by a calcium electrode. Incorporation of the IIb-IIIa complex produced significant facilitation of Ca2+ movement across the lipid bilayer. No net transmembrane Ca2+ movement was seen with dissociated IIb and IIIa. Movement of Ca2+ was proportional to the transmembrane Ca2+ gradient. Ca2+ movement into the vesicles was inversely proportional to extravesicular NaCl from 25 to 150 mmol/L, analogous to several studies in the intact platelet. Adenosine triphosphate had no effect on Ca2+ movement into or out of the vesicles. Specific inhibition of a Ca2+ shift into the vesicles was seen with M148, a monoclonal antibody to IIb/IIIa, while no inhibition was observed with a panel of other anti-IIb/IIIa monoclonal antibodies. This suggests that a specific site on the complex or orientation of the complex is essential for calcium channel function. These data demonstrate that the GPIIb/IIIa complex can serve as a passive Ca2+ channel across a phospholipid bilayer and has the potential to play a role in Ca2+ flux across the platelet plasma membrane. |
| Related Links | https://ashpublications.org/blood/article-pdf/72/2/714/218020/714.pdf |
| Ending Page | 720 |
| Page Count | 7 |
| Starting Page | 714 |
| DOI | 10.1182/blood.v72.2.714.bloodjournal722714 |
| Journal | Blood |
| Issue Number | 2 |
| Volume Number | 72 |
| Language | English |
| Publisher | American Society of Hematology |
| Publisher Date | 1988-08-01 |
| Access Restriction | Open |
| Subject Keyword | Biochemistry and Molecular Biology Antibody Transmembrane Function Glycoproteins Vesicles Proportional Gpiib Fura Iib/iiia Journal: Blood (Vol- 54, Issue- 2) |
| Content Type | Text |
| Resource Type | Article |
