1995 Fiscal Year Final Research Report Summary
Dynamics of vesicular tronsformation in maclear complex.
| Project/Area Number |
06557004
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General physiology
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| Research Institution | Jichi Medical School |
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Principal Investigator |
MARUYAMA Yoshio Jichi Medical School, Physiology, Subprofesror, 医学部, 助教授 (00133942)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Endoplasmic reticulum / Patch-clamp / Ion channel / Membrane capacitance / Budding / Lumenal calcium |
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| Research Abstract |
The outer nuclear membrane of pancreatic acinar cells serves as a rough endoplasmic reticulum (ER) membrane. Collecting nuclear envelopes by enucleation, the standard patch-clamp techniques were applied to the outer membrane of these preparation. At the single channel and whole-current level, 1) voltage and Ca^<2+>-activated large K-channel current, 2) a type of outward-going rectifier K-channel current, 3) a type of inward-going rectifier Cl-channel current, were found. These channels may contribute to cellular Ca^<2+>-signaling through regulating IP_3-and/or cyclic ADP-ribose-dependent Ca^<2+>-release from the ER.Applying a phase-sensitive capacitance measurement to the ER preparation, the time course of the changes in membrane capacitance were monitored. At the local patch-membrane level, the changes occurred at random as discrete on-and off-steps, which can be interpreted as reversible vesicle formation (membrane transformation). The size distribution of the steps were fitted by a negative exponential curve, suggesting the membrane transformation energy seems to have a single energy peak. Increasing the lumenal Ca^<2+>-concentration at the whole-ER level, a rise in the membrane capacitance was found. This indicates that the vesicles are reversibly transformed to caps with a connection between the vesicle interior and the ER lumen. The result suggests the involvement of the ER lumenal Ca^<2+> in the vesicular transport.
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