Four Variant Chicken Erythroid AE1 Anion Exchangers
ROLE OF THE ALTERNATIVE N-TERMINAL SEQUENCES IN INTRACELLULAR TARGETING IN TRANSFECTED HUMAN ERYTHROLEUKEMIA CELLS (*)
- From the Department of Microbiology and Immunology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
- §To whom correspondence should be addressed: Dept. of Microbiology and Immunology, University of Tennessee, Memphis, 858 Madison Ave., Memphis, TN 38163. Tel.: 901-448-7080; Fax: 901-448-8462.
Abstract
Four variant AE1 anion exchangers with predicted molecular masses of 
99, 
102, 
104, and 
108 kDa are expressed in chicken erythroid cells. These variant polypeptides differ in sequence only at the N terminus of
their cytoplasmic domains. Molecular analyses have shown that transcripts derived from both of the erythroid-specific promoters,
P1 and P2, encode all four of these AE1 anion exchanger variants. However, quantitative RNase protection analyses have shown
that the transcripts derived from the P1 promoter are much more prevalent than those derived from the P2 promoter. Reverse
transcriptase polymerase chain reaction studies have indicated that the extensive diversity in the transcripts derived from
the AE1 gene occurs both in primitive and definitive lineage erythroid cells. Transient transfection analyses using human
erythroleukemia cells have investigated the functional significance of the alternative sequences at the N terminus of these
variant exchangers. These studies have shown that the erythroid AE1 variants are sorted to different membrane compartments
in these cells. The 
99- and 
102-kDa variants are primarily sorted to the plasma membrane, whereas the 
108-kDa variant is retained in a perinuclear compartment. These results suggest that the alternative N-terminal cytoplasmic
sequences of these polypeptides may serve as signals to direct these variant transporters to different membrane compartments
within cells.
Footnotes
-
↵* This research was supported by Grant 91-009920 from the National Chapter of the American Heart Association, Grant IN-176-B from the American Cancer Society (to J. V. C.), and a grant from the National Kidney Foundation of West Tennessee, Inc. (to K. H. C.). Oligonucleotides and peptides were provided by the Molecular Resource Center Synthesis Facility, University of Tennessee, Memphis. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1K. H. Cox and J. V. Cox, unpublished observations.
-
↵2 The abbreviations used are:
- HEL
-
human erythroleukemia
- RT
-
reverse transcriptase
- PCR
-
polymerase chain reaction
- RACE
-
rapid amplication of cDNA ends
- PIPES
-
1,4-piperazinediethanesulfonic acid
- PBS
-
phosphate-buffered saline.
-
↵3J. Cox, unpublished observations.
-
- Received December 13, 1994.
- Revision received May 5, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
