Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

FcgammaRI requires both the intracellular domain of the alpha-chain and associated leukocyte Fc receptor (FcR) gamma-chains for its biological function. We recently found the C terminus of periplakin to selectively interact with the cytoplasmic domain of the FcgammaRI alpha-chain. It thereby enhances the capacity of FcgammaRI to bind, internalize, and present antigens on MHC class II. Here, we characterized the domains involved in FcgammaRI-periplakin interaction using truncated and alanine-substituted FcgammaRI mutants and randomly mutagenized periplakin. This allowed us to design TAT peptides that selectively interfered with endogenous FcgammaRI-periplakin interactions. The addition of these peptides to FcgammaRI-expressing cells modulated FcgammaRI ligand binding, as assessed by erythrocyte-antibody-rosetting. These data support a dominant-negative role of C-terminal periplakin for FcgammaRI biological activity and implicate periplakin as a novel regulator of FcgammaRI in immune cells.
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PMID:Modulation of FcgammaRI (CD64) ligand binding by blocking peptides of periplakin. 1516 26

Here, we report that the MHC class I-related neonatal Fc receptor (FcRn) is expressed within azurophilic and specific granules of neutrophils and relocates to phagolysosomes on phagocytosis of IgG-opsonized bacteria. We found FcRn to enhance phagocytosis in a pH-dependent manner which was independent of IgG recycling. IgG-opsonized bacteria were inefficiently phagocytosed by neutrophils from beta2M knock-out or FcRn alpha-chain knock-out mice, which both lack expression of FcRn. Similarly, low phagocytic activity was also observed with mutated IgG (H435A), which is incapable of binding to FcRn, while retaining normal binding to classical leukocyte Fcgamma receptors. Finally, a TAT peptide representing intracellular endocytosis and transport motifs within FcRn strongly inhibited IgG-mediated phagocytosis. These findings support a novel concept in which FcRn fulfills a major role in IgG-mediated phagocytosis.
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PMID:FcRn: an IgG receptor on phagocytes with a novel role in phagocytosis. 1684 38