Identification and functional characterization of a TIA-1-related nucleolysin.
We recently reported the molecular cloning of a cytotoxic granule-associated RNA-binding protein designated TIA-1. The ability of recombinant TIA-1 to induce DNA fragmentation in permeabilized cells suggested that this protein is the granule component responsible for inducing apoptosis in cytolytic lymphocyte (CTL) targets. Here we report the characterization of a cDNA encoding a TIA-1-related protein designated TIAR. The deduced amino acid sequence of TIAR reveals it to be a 42-kDa protein possessing three RNA-binding domains and a carboxyl-terminal auxiliary domain. Although the RNA-binding domains of TIA-1 and TIAR share greater than 85% amino acid homology, their carboxyl-terminal auxiliary domains are only 51% homologous. The carboxyl terminus of TIAR contains a lysosome-targeting motif, indicating that TIAR is probably a cytotoxic granule-associated protein. Like TIA-1, purified recombinant TIAR induced DNA fragmentation in permeabilized target cells. Although immunoblotting analysis of post-nuclear supernatants revealed TIA-1 protein to be restricted to CTLs, PCR analysis revealed the expression of TIA-1 and TIAR mRNA transcripts in a wide variety of cell types. Our data suggest that the granules of CTLs contain at least two candidate nucleolysins involved in CTL killing.
Kawakami
A
A
Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, MA 02115.
Tian
Q
Q
Duan
X
X
Streuli
M
M
Schlossman
S F
SF
Anderson
P
P
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D015139:Blotting, Southern; D002467:Cell Nucleus / Q000187:drug effects*; D003001:Cloning, Molecular; D016384:Consensus Sequence; D003602:Cytotoxicity, Immunologic; D004247:DNA / Q000235:genetics; D004249:DNA Damage; D015870:Gene Expression; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D039102:Poly(A)-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D000074019:T-Cell Intracellular Antigen-1
D000911:Antibodies, Monoclonal; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000074019:T-Cell Intracellular Antigen-1; C071558:TIA1 protein, human; C076751:TIAL1 protein, human; D004247:DNA