|
|
 Previous Article | Table of Contents | Next Article 
Expression of transcobalamin II receptors by human leukemia K562 and HL- 60
cells
T Amagasaki, R Green and DW Jacobsen
Department of Laboratory Hematology, Cleveland Clinic Foundation, OH
44195-5139.
Plasma membrane receptors for the serum cobalamin-binding protein
transcobalamin II (TCII) were identified on human leukemia K562 and HL- 60
cells using immunoaffinity-purified human TCII labeled with
[57Co]cyanocobalamin. The Bmax values for TCII receptors on proliferating
K562 and HL-60 cells were 4,500 and 2,700 per cell, respectively.
Corresponding dissociation constants (kd) were 8.0 x 10(- 11) mol/L and 9.0
x 10(-11) mol/L. Rabbit TCII also bound to K562 and HL-60 cells but with
slightly reduced affinities. Calcium was required for the binding of
transcobalamin II to K562 cells. Brief treatment of these cells with
trypsin resulted in almost total loss of surface binding activity. After
removal of trypsin, surface receptors for TCII slowly reappeared, reaching
pretrypsin treatment densities only after 24 hours. Reappearance of
receptors was blocked by cycloheximide. TCII receptor densities on K562 and
HL-60 cells correlated inversely with the concentration of cobalamin in the
culture medium. This suggests that intracellular stores of cobalamin may
affect the expression of transcobalamin receptors. Nonproliferating
stationary-phase K562 cells had low TCII receptor densities (less than
1,200 receptors/cell). However, the density of TCII receptors increased
substantially when cells were subcultured in fresh medium. Up-regulation of
receptor expression coincided with increased 3H-thymidine incorporation,
which preceded the resumption of cellular proliferation as measured by cell
density. In the presence of cytosine arabinoside, which induces erythroid
differentiation, K562 cells down-regulated expression of TCII receptors.
When HL-60 cells were subcultured in fresh medium containing
dimethysulfoxide to induce granulocytic differentiation, the up- regulation
of TCII receptors was suppressed. This event occurred well before a
diminution of 3H-thymidine incorporation and cessation of proliferation.
Thus, changes in the regulation of expression of TCII receptors correlate
with both the proliferative and differentiation status of cells.
Volume 76,
Issue 7,
pp. 1380-1386,
10/01/1990
Copyright © 1990 by The American Society of Hematology
 CiteULike  Connotea  Del.icio.us  Digg  Reddit  Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
D. W. Jacobsen and A. V. Glushchenko
The transcobalamin receptor, redux
Blood,
January 1, 2009;
113(1):
3 - 4.
[Full Text]
[PDF]
|
|
|
|
|
|
|
E. V. Quadros, Y. Nakayama, and J. M. Sequeira
The protein and the gene encoding the receptor for the cellular uptake of transcobalamin-bound cobalamin
Blood,
January 1, 2009;
113(1):
186 - 192.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. T. Greipp, D. A. Collins, S. J. Russell, M. E. Harvey, A. Goel, and P. R. Greipp
In-111DAC Is a Novel Technique To Image Multiple Myeloma.
Blood (ASH Annual Meeting Abstracts),
November 16, 2006;
108(11):
3488 - 3488.
[Abstract]
[PDF]
|
|
|
|
|
|
|
T. Fiskerstrand, B. Riedel, P. M. Ueland, B. Seetharam, E. H. Pezacka, S. Gulati, S. Bose, R. Banerjee, R. K. Berge, and H. Refsum
Disruption of a Regulatory System Involving Cobalamin Distribution and Function in a Methionine-dependent Human Glioma Cell Line
J. Biol. Chem.,
August 7, 1998;
273(32):
20180 - 20184.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
G. R. McLean, E. V. Quadros, S. P. Rothenberg, A. C. Morgan, J. W. Schrader, and H. J. Ziltener
Antibodies to Transcobalamin II Block In Vitro Proliferation of Leukemic Cells
Blood,
January 1, 1997;
89(1):
235 - 242.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
