# CELL SURFACE CONTROL OF LYMPHOCYTE PHYSIOLOGY

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 1987 · $214,065

## Abstract

The objective of this research is to learn how actin interacts with plasma
membrane.  Three examples of actin-membrane linkages are being studied.
(1) We are determining the molecular composition of the actin to membrane
cross filament in intestinal microvilli.  a) We propose to isolate the
microvillar 110K protein, a candidate for the cross filament, and to
determine whether and how it interacts with actin and the microvillar
membrane in vitro.  b) We will test the proposed roles of the microvillar
core proteins (fimbrin, villin, 110K, actin, and calmodulin) in the
structure and membrane association of the core bundle of actin filaments by
immunoultrastructural localization of these proteins in situ, using 50
angstroms Fab' fragments of monoclonal antibodies complexed to 50 angstroms
gold particles.  c) We will screen for microvillar proteins which link
actin to membrane by a reconstitution binding assay employing 3H-actin,
microvillar membranes, and fractionated microvillar proteins.  (2) We are
analyzing the association of vinculin-like proteins with the plasma
membrane.  We have discovered two new proteins in smooth muscle, 150K
meta-vinculin, and 300K vinculin-like polypeptide (300K-VLP) that are
antigenically related to 130K vinculin, but which unlike vinculin, have
solubility properties of amphiphilic membrane proteins and could be direct
links between actin filaments and the cell membrane.  We propose to analyze
the molecular basis for the antigenic similarity and solubility difference
between these proteins by peptide mapping, charge shift electrophoresis,
biosynthetic labelling and pulse-chase experiments, isolation of native
metavinculin and 300K-VLP and characterization of their interaction with
actin, plasma membrane and liposomes in vitro.  (3) We have defined a cell
surface actin (CSA) on some murine lymphocytes by immunofluorescence and
flow cytometry.  a) We propose to determine by two-color immunofluorescence
and flow cytometry if CSA is a marker for new murine and human lymphocyte
subpopulations within the known subdivisions of T and B-cells.  b) We will
assay for biochemical differences between CSA and intracellular actin by
determining if CSA is a glycoprotein and if it has a hydrophobic domain.
c) We plan to test for the possible function of CSA in mediating adherence
of lymphocytes to fibronectin and to cells of the lymphoreticuloendothelial
system, and for the possible function of CSA as part of a cell surface
growth control complex.

## Key facts

- **NIH application ID:** 3125532
- **Project number:** 5R01AI013700-11
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **SAM.gov UEI:** FTMTDMBR29C7
- **Principal Investigator:** SUSAN W CRAIG
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $214,065
- **Award type:** 5
- **Project period:** 1977-08-01 → 1988-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3125532

## Citation

> US National Institutes of Health, RePORTER application 3125532, CELL SURFACE CONTROL OF LYMPHOCYTE PHYSIOLOGY (5R01AI013700-11). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3125532. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*