Molecular Immunology 42 (2005) 1485–1493
Porcine TCR CD3-chain and -chain
Ryuji Yamamoto
a,b
, Tamaki Isobe
b
, Tomoko Eguchi
b
, Wei-Ran Tang
c
,
Nobutaka Kiyokawa
c
, Hiroshi Amemiya
d
, Junichiro Fujimoto
c
,
Eimei Sato
a
, Yohtaroh Takagaki
e
, Hiroshi Yasue
b,∗
a
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumi-dori Amamiya-machi, Aoba, Sendai 981-8555, Japan
b
Genome Research Department, National Institute of Agrobiological Sciences, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan
c
Department of Developmental Biology, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo 154-8567, Japan
d
Department of Innovative Surgery, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo 154-8567, Japan
e
Department of Molecular Genetics, Graduate School of Medical Sciences, Kitasato University, 1-15-1 Kitasato, Sagamihara, 228-8555, Japan
Received 5 October 2004; accepted 18 January 2005
Available online 16 March 2005
Abstract
Complete porcine CD3-chain cDNA sequence was obtained for the first time, and its genomic nucleotide sequence was investigated from
exon 2 down to CD3-chain exon 8. The sequence of porcine CD3-chain showed homologous amino acid sequence with human and murine
counterparts, in contrast to CD3-chain exon 8 with diversity among animals previously investigated. CD3-chain peptide is an alternative
splice form of CD3-chain exon 7 splicing to CD3-chain exon 8 instead of CD3-chain exon 8. The genomic sequences revealed that the
splice acceptor sequences of CD3-chain exon 8 of all animals investigated to be completely uniform. Further, CD3-chain exon 8 amino
acid sequences retained the unique characters of having high proline (Pro) and positively charged amino acid content except for rats and
mice. Although the biological role of CD3-chain remains to be enigmatic, these evidences suggests the evolutional pressure to maintain its
sequence.
© 2005 Elsevier Ltd. All rights reserved.
Keywords: Swine; CD3; CD3; Alternative splicing
1. Introduction
Antigen specific immune response is initiated by the
recognition of foreign antigen (Ag) by T cell receptor (TCR)
complex. The TCR complex consists of clonotypic Ag recog-
nition elements, either TCR - and -chain heterodimers or
TCR - and -chain heterodimers, and a group of invariant
subunits including the three related CD3 components (-,
-, and -chains), and the structurally distinct CD3-chain.
Although T-cells and T-cells are known to recognize
antigens in different manner, both sets of clonotypic TCR
heterodimers are complexed with common CD3 chain fam-
ily members (Baniyash et al., 1988; Borst et al., 1983a,b;
Oettgen et al., 1986; Samelson et al., 1985).
∗
Corresponding author. Tel.: +81 29 838 8664; fax: +81 29 838 8674.
E-mail address: hyasue@affrc.go.jp (H. Yasue).
The CD3-chain (also called TCR-chain) and CD3-
chain are most recently identified member among the CD3
chain family members (Weissman et al., 1986). In mice,
large majority (∼90%) of CD3-chains exist as disulfide-
linked CD3–CD3 homodimers, with the remainder being
CD3–CD3 (Baniyash et al., 1988) heterodimers. Occa-
sionally, trace amount of CD3–FcR-chains, also disulfide-
linked heterodimers, are detected (Samelson, 2002; Veillette
et al., 2002). CD3-chain gene is known to have 8 exons, and
CD3-chain is an alternatively spliced product composed of
CD3-chain gene exons 1–7 with 3
′
end splicing to CD3
exon 8 located 3
′
down stream of CD3-chain exon 8.
Although CD3-chain is not an absolute requirement for
the T-cell development (Liu et al., 1997, 1993; Love et al.,
1993; Shores et al., 1997a, 1994; Shores and Love, 1997),
CD3-chain is critical for the selection of the TCR repertoire
and for the prevention of autoimmunity (Lin et al., 1997;
0161-5890/$ – see front matter © 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.molimm.2005.01.008