# A-SYSTEM AMINO ACID TRANSPORT AND PROTEIN KINASE C

> **NIH NIH R01** · LOCKHEED MARTIN ENERGY SYSTEMS, INC. · 1987 · $138,993

## Abstract

LLC-PK1 is an epithelioid cell line that differentiates transport
functions in postconfluent cells.  A-system amino acid transport is very
active in rapidly growing cells, but is stepped down to stable levels in
postconfluent cells while Na+-dependent hexose transport develops to a
high degree.  The tumor promoter TPA rapidly reactivates the A-system.  TPA
also activates protein kinase C (C-kinase), a Ca++-\and
phosphatidylserine-dependent kinase activated by diacylglycerols (DG).  TPA
can substitute for DG.  Certain DG analogs will also reactivate the
A-system in vivo.  In LLC-PK1 cells, TPA treatment leads to
redistribution of C-kinase from cytosol to the particulate (membranes and
organelles) fraction.  By fractionation experiments, the cellular loci of
TPA-dependent redistribution will be defined more closely and compared to
the effects of the DG analogs.  Fluorescent and colloidal gold-labeled
antibodies to purified C-kinase will be used in both light and electron
microscopy, respectively, to examine C-kinase localization in untreated,
TPA-treated, and lipid-treated postconfluent cells.  Basolateral membranes
(locus of the A-system) and/or endocytic vesicles will be isolated and the
A-system reactivated in vitro in transporting vesicles with exogenous
C-kinase and TPA or bioactive DG analogs.  In cells and isolated membranes,
the proteins phosphorylated by TPA-\or DG-activated C-kinase will be
identified by electrophoretic analysis.  The proposed research is designed
to increase our understanding of fundamental mechanisms of tumor promotion,
including the reactivation of quiescent, differentiated cells back into a
rapidly growing state.  (S)

## Key facts

- **NIH application ID:** 3179767
- **Project number:** 5R01CA040165-03
- **Recipient organization:** LOCKHEED MARTIN ENERGY SYSTEMS, INC.
- **Principal Investigator:** JOHN S COOK
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $138,993
- **Award type:** 5
- **Project period:** 1985-08-01 → 1989-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3179767

## Citation

> US National Institutes of Health, RePORTER application 3179767, A-SYSTEM AMINO ACID TRANSPORT AND PROTEIN KINASE C (5R01CA040165-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3179767. Licensed CC0.

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