STRUCTURE - FUNCTION OF THE HUMAN TRANSFERRIN RECEPTOR

Project: Research project

Project Details

Description

The goals of this proposal are to define the role of glycosylation
and of intracellular proteins in the correct folding and transport
of the transferrin receptor to the cell surface. These studies
will provide information concerning the mechanisms of protein
transport and intra- and inter-protein signalling. The uptake of iron into mammalian cells involves the binding of
transferrin, the serum iron transport protein, to the transferrin
receptor, followed by the internalization of the receptor-
transferrin complex. Iron uptake is essential for cell division.
The receptor has been identified as a proliferation specific
marker. Rapidly proliferating cells have higher iron requirements
than non-dividing cells (that do not have differentiated functions
for iron) and have higher numbers of these receptors. Prior studies using tunicmycin-treated A431 cells have demonstrated
that the unglycosylated form of the transferrin receptor does nth
form intersubunit disulfide bonds, does not bind transferrin, is
not transported to the cell surface and is found associated in a
complex with two proteins (Mr=130/135kd). The first aim of this proposal is to define the composition and
function of the transferrin receptor-130/135kd proteins complex.
Crosslinking studies will be used to determine whether other
proteins are associated with this complex. The intracellular
location of the unglycosylated receptor will be determined by
immunohistolocalization as well as subcellular fractionation to
establish whether it is associated with specific subcellular
organelles. The complex will be further characterized with respect
to its stability and protein interactions to determine if the
130/135kd proteins could have similarities to the family of heat
shock-stress proteins. The second aim of this proposal is to study the 130/135kd proteins
directly to determined their function. They will be purified and
partial sequences of them will be compared with protein data bases.
Antibodies will be generated against them to permit the examination
and quantification of the 130/135kd proteins in untreated cells
and to establish if they ar associated with the nascent transferrin
receptor. The third aim is to determined the role of asparagine-linked
glycosylation in the correct folding and transport of the newly
synthesized receptor to the cell surface. This will be approached
by using site-directed mutagenesis which will test the contribution
of each of the three asparagine-linked glycosylation sites.
StatusFinished
Effective start/end date7/1/896/30/04

Funding

  • National Institutes of Health: $255,043.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $27,782.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $122,928.00
  • National Institutes of Health
  • National Institutes of Health: $239,721.00
  • National Institutes of Health
  • National Institutes of Health: $247,603.00
  • National Institutes of Health: $29,940.00
  • National Institutes of Health

ASJC

  • Medicine(all)

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