Genomic organization and expression of TREM-like genes in the human and mouse, and comparison of the predicted amino acid sequences of mouse and human TLT-1 sequences.

(A) Schematic showing the relationship of the human TREM cluster (top) and the mouse TREM cluster (bottom). (B) The exon structure of the TLT-1 gene is shown. The blackened area of exon 2 represents the deletion caused by the alternative splice event detected by RT-PCR in RAW264.7 cells and dendritic cell cultures. The asterisk denotes the premature stop in this smaller mRNA species. (C) The predicted amino acid sequences of murine TLT-1 (mTLT-1) and human TLT-1 (hTLT-1). The leader sequence is bolded, the cystines forming disulfide bonds within the Ig V-type domain are boxed with dotted lines, potential O-glycosolation sites are marked by “Ŝ” for serines or “Ť” for theonines, the transmembrane domain is underlined, polyproline-rich region is boxed, and the ITIM sequence is boxed in gray. Asterisk indicates stop codon. (D) Northern expression of TREM-like genes in bone marrow (lane 1), lung (lane 2), lymph node (lane 3), testis (lane 4), and thymus (lane 5). (E) Northern expression of TREM-like genes in RAW264.7 (lane 1) and P815 (lane 2).