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Cloning of a new lectin-like receptor expressed on human NK cells
K S Boles1, R Barten, P R Kumaresan
1Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107-2699, USA.
Abstract:
Natural killer (NK) cells constitute the third major population of lymphocytes. They possess the inherent capacity to kill various tumor and virally infected cells and mediate the rejection of bone-marrow grafts in lethally irradiated animals. A large family of NK cell receptors belong to the C-type lectin superfamily and are localized to the NK gene complex on Chromosome (Chr) 6 in the mouse and Chr 12 in the human. Genes in the NK gene complex encode type II receptors and examples include the families of NKR-P1, Ly-49, and NKG2 receptors. Examples of other C-type lectin-like NK cell receptors that occur as individual genes are CD94, CD69, and AICL. Here we report the molecular characterization and chromosomal mapping of a human lectin-like transcript (LLT1) expressed on NK, T, and B cells and localized to the NK gene complex within 100 kilobases of CD69. The cDNA encodes a predicted protein of 191 amino acid residues with a transmembrane domain near the N-terminus and an extracellular domain of 132 amino acid residues with similarity to the carbohydrate recognition domain of C-type lectins. The predicted protein of LLT1 shows 59 and 56% similarity to AICL and CD69, respectively. The predicted protein does not contain any intracellular ITIM motifs, suggesting that LLT1 may be involved in mediating activation signals.
Insights
Researchers identified a novel lectin-like transcript 1 (LLT1) on immune cells. This gene, located on human chromosome 12, may play a role in immune cell activation signals.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- Natural killer (NK) cells are crucial lymphocytes with cytotoxic and graft rejection capabilities.
- NK cell receptors, including C-type lectin superfamily members, are key to their function.
- These receptors are often located in the NK gene complex on human chromosome 12.
Purpose of the Study:
- To molecularly characterize and map the chromosomal location of a novel human lectin-like transcript 1 (LLT1).
- To investigate the expression profile and potential function of LLT1 in immune cells.
Main Methods:
- Molecular characterization of the LLT1 cDNA.
- Chromosomal mapping of the LLT1 gene.
- Analysis of predicted protein structure and similarity to known NK cell receptors.
Main Results:
- LLT1 is expressed on NK, T, and B cells.
- The LLT1 gene is located on human chromosome 12 within the NK gene complex, near CD69.
- The predicted LLT1 protein shares similarity with AICL and CD69 and lacks intracellular ITIM motifs.
Conclusions:
- LLT1 represents a newly identified C-type lectin-like molecule expressed on human lymphocytes.
- Its genomic location and structural features suggest a role in immune cell signaling, potentially mediating activation signals.