BIO - TERMS - PEPTIDE Flashcards
(46 cards)
affinity hypothesis
Hypothesis that proposes how the choice between negative selection and positive selection of T cells in the thymus is made, according to the strength of self-peptide:MHC binding by the T-cell receptor. Low-affinity interactions rescue the cell from death by neglect, leading to positive selection; high-affinity interactions induce apoptosis and thus negative selection.
amyloid-b peptides
Plaques and neurofibrillary tangles in brain tissue found in Alzheimer’s disease. amyloid precursor protein Precursor to amyloid-b peptides found in brain tissue of Alzheimer’s disease. amylopectin Starch consisting of straight chains of glucose with branching.
antimicrobial peptide (AMP)
An antibiotic that is bactericidal and has a broad spectrum of activity; see bacteriocin.
antimicrobial peptides, antimicrobial proteins
Amphipathic peptides or proteins secreted by epithelial cells and phagocytes that kill a variety of microbes nonspecifically, mainly by disrupting cell membranes. Antimicrobial peptides in humans include the defensins, the cathelicidins, the histatins, and RegIIIγ.
bradykinin
A vasoactive peptide that is produced as a result of tissue damage and acts as an inflammatory mediator.
C-peptide
A biologically inactive fragment of proinsulin that is released together with insulin.
C1 inhibitor (C1INH)
An inhibitor protein for C1 that binds and inactivates C1r:C1s enzymatic activity. Deficiency in C1INH causes hereditary angioedema through production of vasoactive peptides that cause subcutaneous and laryngeal swelling.
calprotectin
A complex of heterodimers of the antimicrobial peptides S100A8 and S100A9, which sequester zinc and manganese from microbes. Produced in abundance by neutrophils, and in lesser amounts by macrophages and epithelial cells.
cathelicidins
Family of antimicrobial peptides that in humans has one member.
cell wall
The outer covering of most bacterial, fungal, algal, and plant cells; in bacteria, it consists of peptidoglycan.
class I MHC protein
One of two classes of major histocompatibility complex (MHC) protein. Found on the surface of almost all vertebrate cell types, where it can present foreign peptides derived from a pathogen such as a virus to cytotoxic T cells.
class II-associated invariant chain peptide (CLIP)
A peptide of variable length cleaved from the invariant chain (Ii) by proteases. It remains associated with the MHC class II molecule in an unstable form until it is removed by the HLA-DM protein.
Competence (Com) proteins
Proteins that mediate the process of transformation in bacteria. Their synthesis is induced by small peptides called competence pheromones.
cryptdins
α-Defensins (antimicrobial peptides) made by the Paneth cells of the small intestine.
default pathway
The transport pathway of proteins directly to the cell surface via the nonselective constitutive secretory pathway, entry into which does not require a particular signal. defensin Positively charged, amphipathic, antimicrobial peptide—secreted by epithelial cells—that binds to and disrupts the membranes of many pathogens.
Edman degradation
A method for N-terminal sequencing of peptide chains by treatment with N-phenylisothiocyanate.
ER signal sequence
N-terminal signal sequence that directs proteins to enter the endoplasmic reticulum (ER). Cleaved off by signal peptidase after entry.
ERp57
A chaperone protein involved in loading peptide onto MHC class I molecules in the endoplasmic reticulum.
fMet-Leu-Phe (fMLF) receptor
A pattern recognition receptor for the peptide fMet-Leu-Phe, which is specific to bacteria, on neutrophils and macrophages. fMet-Leu-Phe acts as a chemoattractant.
Grass
A serine protease of Drosophila that functions downstream of peptidoglycan-recognition proteins (PGRPs) and Gram-negative binding proteins (GNBPs) to initiate the proteolytic cascade leading to Toll activation.
H2-M3
A nonclassical MHC class Ib protein in mice that can bind and present peptides having an N-formylated amino terminus for recognition by CD8 T cells.
histatins
Antimicrobial peptides constitutively produced by the parotid, sublingual, and submandibular glands in the oral cavity. Active against pathogenic fungi such as Cryptococcus neoformans and Candida albicans.
HLA-DM
An invariant MHC protein resembling MHC class II in humans that is involved in loading peptides onto MHC class II molecules. A homologous protein in mice is called H-2M, or sometimes H2-DM.
Imd (immunodeficiency) signaling pathway
A defense against Gramnegative bacteria in insects that results in the production of antimicrobial peptides such as diptericin, attacin, and cecropin.
