Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17931 (galectin-3)
 2,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Group A Streptococcus has evolved numerous mechanisms to evade the host immune system to survive, disseminate, and cause disease. Recently a secreted protein named Mac-1 was identified and shown to enhance survival of the pathogen. A new variant of Mac-1 (designated Mac-2) also was recently described and shown to differ from Mac-1 by approximately 50% amino acid sequence divergence in the middle one-third of the molecule. To gain new information about the role of Mac-1 and Mac-2 in host-pathogen interactions, solution binding experiments were performed using surface plasmon resonance and purified Mac proteins. Mac-1 bound the same lower hinge region of human IgG as Fc receptors with 2.5 microM affinity, which lead to proteolytic cleavage of the antibody. Similar Km (6.8-18.9 microM) and kcat (0.02-0.13 s(-1)) values of the Mac-1 endopeptidase activity were obtained for IgG1, IgG2, IgG3, and IgG4. Mac-2 variant, in contrast, bound human IgG poorly (KD = 16 mM) and had weak endopeptidase activity against IgG. Instead, Mac-2 bound FcgammaRII and FcgammaRIII with 5 and 75 microM affinity, respectively. This binding competitively blocked IgG from recognition by Fc receptors. Taken together, Mac proteins block immunoglobulin recognition by Fc receptors and degrade immunoglobulins, thereby enhancing survival of the pathogen through the inhibition of phagocytosis, endocytosis of IgG-opsonized particles, and antibody-dependent cell-mediated cytotoxicity. Consequently, these proteins may be potential therapeutic targets.
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PMID:Insight of host immune evasion mediated by two variants of group a Streptococcus Mac protein. 1546 62

Galectin-3 belongs to a family of galectins, evolutionarily conserved glycan binding proteins (lectins) that have recently attracted much attention as modulators in adaptive immune responses. Previously, galectins have been considered lectins that bind only to endogenous "self" glycans. Further, galectins are synthesized and stored in the cytosol, where there are virtually no glycan-containing proteins, raising doubts over the biological significance of their glycan binding capacity. As discussed in this review, with particular emphasis on the role of galectin-3 in the innate immune response against the protozoan parasite Leishmania, several recent studies have suggested that galectin-3 could recognize L. major-specific pathogen-associated molecular pattern and, in parallel, facilitate the infiltration of neutrophils to the infected sites that helps reduce the initial parasite burden once galectin-3 is released as a damage-associated molecular pattern. Thus, while further investigation is necessary, based on the current results, it could be proposed that galectin-3 can hinge two areas of the innate immune recognition system, DAMP and PAMP pathways in the early host responses against various pathogens.
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PMID:Role of galectin-3 in the initial control of Leishmania infection. 2494 Sep 13