Human erythrocyte band 3 becomes rapidly phosphorylated on tyrosine residues after exposure of erythrocytes to hypertonic conditions. The driving force for this phosphorylation reaction seems to be a decrease in cell volume, because (1) changes in band 3 phosphotyrosine content accurately track repeated changes in erythrocyte volume through several cycles of swelling and shrinking; (2) the level of band 3 phosphorylation is independent of the osmolyte employed but strongly sensitive to the magnitude of cell shrinkage; and (3) exposure of erythrocytes to hypertonic buffers under conditions in which intracellular osmolarity increases but volume does not change (nystatin-treated cells) does not promote an increase in tyrosine phosphorylation. We hypothesize that shrinkage-induced tyrosine phosphorylation results either from an excluded-volume effect, stemming from an increase in intracellular crowding, or from changes in membrane curvature that accompany the decrease in cell volume. Although the net phosphorylation state of band 3 is shown to be due to a delicate balance between a constitutively active tyrosine phosphatase and constitutively active tyrosine kinase, the increase in phosphorylation during cell shrinkage was demonstrated to derive specifically from an activation of the latter. Further, a peculiar inhibition pattern of the volume-sensitive erythrocyte tyrosine kinase that matched that of p72syk, a tyrosine kinase already known to associate with band 3 in vivo, suggested the involvement of this kinase in the volume-dependent response.
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October 1998
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Research Article|
October 15 1998
Characterization of the hypertonically induced tyrosine phosphorylation of erythrocyte band 3
Giampaolo MINETTI;
Giampaolo MINETTI
1
*Dipartimento di Biochimica ‘A. Castellani ’, Università di Pavia, Via Bassi 21, I-27100 Pavia, Italy
1To whom correspondence should be addressed (e-mail bioscipa@unipv.it).
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Claudio SEPPI;
Claudio SEPPI
*Dipartimento di Biochimica ‘A. Castellani ’, Università di Pavia, Via Bassi 21, I-27100 Pavia, Italy
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Annarita CIANA;
Annarita CIANA
*Dipartimento di Biochimica ‘A. Castellani ’, Università di Pavia, Via Bassi 21, I-27100 Pavia, Italy
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Cesare BALDUINI;
Cesare BALDUINI
*Dipartimento di Biochimica ‘A. Castellani ’, Università di Pavia, Via Bassi 21, I-27100 Pavia, Italy
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Philip S. LOW;
Philip S. LOW
†Department of Chemistry, Purdue University, West Lafayette, IN, U.S.A.
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Augusta BROVELLI
Augusta BROVELLI
*Dipartimento di Biochimica ‘A. Castellani ’, Università di Pavia, Via Bassi 21, I-27100 Pavia, Italy
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Publisher: Portland Press Ltd
Received:
May 11 1998
Revision Received:
July 24 1998
Accepted:
August 14 1998
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 335 (2): 305–311.
Article history
Received:
May 11 1998
Revision Received:
July 24 1998
Accepted:
August 14 1998
Citation
Giampaolo MINETTI, Claudio SEPPI, Annarita CIANA, Cesare BALDUINI, Philip S. LOW, Augusta BROVELLI; Characterization of the hypertonically induced tyrosine phosphorylation of erythrocyte band 3. Biochem J 15 October 1998; 335 (2): 305–311. doi: https://doi.org/10.1042/bj3350305
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