Cloning and characterization of 5E6(Ly-49C), a receptor molecule expressed on a subset of murine natural killer cells.

Abstract

5E6 is a cell surface molecule expressed on a subpopulation of murine natural killer (NK) cells that are involved in the specific rejection of H-2d or H-2f (hemopoietic histocompatibility determinant 2) bone marrow cell grafts. Here, we isolated and cloned the gene encoding 5E6 and determined the nucleotide sequence of the cDNA. 5E6 is nearly identical to Ly-49C; the deduced amino acid sequence reveals a polypeptide of 266 amino acids with a molecular weight of 31,284 that contains multiple cysteine residues to explain its disulfide-linked homodimer structure and five potential N-linked glycosylation sites. 5E6 is a type II integral membrane protein with an extracellular carbohydrate recognition domain characteristic of C-type (Ca(2+)-dependent) animal lectins. Chromosomal mapping indicates that 5E6 is located within the NK gene complex on chromosome 6. The sequence of 5E6 mRNA and the degree of glycosylation of 5E6 protein are under genetic control. Immunoprecipitation before removal of N-linked sugars reveals different size molecules. There are several nucleotide differences among BALB/c, B6, and NZB mRNAs; however, none of them would be expected to affect N-glycosylation. Of particular interest are two findings: (a) BALB/c, B6, and (BALB/c x B6)F1 5E6 reduced molecules are approximately 65, 54, and 54 kD, and (b) the cDNA sequence of (BALB/c x B6)F1 is identical to B6. Thus, there appears to be allelic exclusion of 5E6 expression that may be related to the ability of F1 hybrid mice to reject parental H-2d bone marrow cell grafts.

Ly49Q, a member of the Ly49 family that is selectively expressed on myeloid lineage cells and involved in regulation of cytoskeletal architecture

“…These results indicate that phosphorylation of the tyrosine residue in the ITIM is necessary for recruitment of SHP-1 and SHP-2 to Ly49Q. Thus, Ly49Q expressed on COS7 cells shows biochemical characteristics similar to other known Ly49 family members (12,(27)(28)(29).…”

“…2B). Under nonreducing conditions, FLAG-tagged Ly49Q showed an apparent molecular mass of 130 and 220 kDa, indicating that Ly49Q is expressed as dimer or oligomer on the cell surface as in case of other Ly49 family members (27,28). Ly49Q appeared to be N-glycosylated because the treatment with N-glycosidase F reduced its apparent molecular mass (Fig.…”

Liver NK cells expressing TRAIL are toxic against self hepatocytes in mice

“…Ly-49A binds the class I molecules H-2D d , D k , and D p , and Ly-49G2 binds H-2D d and H-2L d . [37][38][39][40][41] These bindings mediate a negative signal to the NK cells, resulting in inhibition of lysis. Recent studies have suggested that these members of the Ly-49 family may also interact with H-2 b molecules.…”

Complete elucidation of a minimal class I MHC natural killer cell receptor haplotype

“…[3][4][5] Cloning and sequencing of Ly49 cDNAs showed that BALB/c NK cells share at least three Ly49-related sequences or alleles with B6 mice: Ly49a, c, and g, although the alleles have diverged and contain a significant number of differences, resulting in several amino-acid substitutions. [6][7][8] The novel activating Ly49L receptor was also found to be expressed in BALB/c mice, but was first identified in the Ly49 haplo-identical CBA and C3H mouse strains. 8,9 The finding of Ly49L supported the contention that all activating receptors have an inhibitory counterpart with a highly similar extracellular domain that has probably arisen by gene hybridization between two different Ly49 genes.…”