HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bengtén, E. Articles by Wilson, M. Search for Related Content PubMed PubMed Citation Articles by Bengtén, E. Articles by Wilson, M.

The IgH Locus of the Channel Catfish, Ictalurus punctatus, Contains Multiple Constant Region Gene Sequences: Different Genes Encode Heavy Chains of Membrane and Secreted IgD¹

Eva Bengtén^2,*, Sylvie M.-A. Quiniou^3,*, Tor B. Stuge^4,*, Takayuki Katagiri^5,*, Norman W. Miller^*, L. William Clem^*, Gregory W. Warr and Melanie Wilson^*

^* Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216; and Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425

The -chain of catfish IgD was initially characterized as a unique chimeric molecule containing a rearranged VDJ spliced to Cµ1, seven C domain-encoding exons (1–7), and a transmembrane tail. The presence of cDNA forms showing splicing of 7 to an exon encoding a secretory tail was interpreted to indicate that membrane (m) and secreted (s) forms were likely expressed from a single gene by alternative RNA processing. Subsequent cloning and sequence analyses have unexpectedly revealed the presence of three C region genes, each linked to a µ gene or pseudogene. The first (IGHD1) is located 1.6 kb 3' of the functional Cµ (IGHM1). The second (IGHD3) is positioned immediately downstream of a pseudo Cµ (IGHM3P), 725 kb 5' of IGHM1. These two genes are highly similar in sequence and each contains a tandem duplication of 2-3-4. However, IGHD1 has a terminal exon encoding the transmembrane region, whereas IGHD3 has a single terminal exon encoding a secreted tail. The occurrence of IGHD3 immediately downstream of a µ pseudogene indicates that the putative s product may not be expressed as a chimeric µ molecule. Western blots and protein sequencing data indicate that an IGHD3-encoded protein is expressed in catfish serum. Thus, catfish m transcripts appear to originate from IGHD1, whereas s transcripts originate from IGHD3 rather than, as previously inferred, from a single expressed gene. The third (IGHD2) is associated with a pseudo Cµ (IGHM2P); its presence is inferred by Southern blot analyses.

This article has been cited by other articles:

				Y. Ohta and M. Flajnik IgD, like IgM, is a primordial immunoglobulin class perpetuated in most jawed vertebrates PNAS, July 11, 2006; 103(28): 10723 - 10728. [Abstract] [Full Text] [PDF]

				J. D. Hansen, E. D. Landis, and R. B. Phillips Discovery of a unique Ig heavy-chain isotype (IgT) in rainbow trout: Implications for a distinctive B cell developmental pathway in teleost fish PNAS, May 10, 2005; 102(19): 6919 - 6924. [Abstract] [Full Text] [PDF]

				Y. Zhao, Q. Pan-Hammarstrom, I. Kacskovics, and L. Hammarstrom The Porcine Ig {delta} Gene: Unique Chimeric Splicing of the First Constant Region Domain in its Heavy Chain Transcripts J. Immunol., August 1, 2003; 171(3): 1312 - 1318. [Abstract] [Full Text] [PDF]