126 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”Antimicrobial peptides: an overview of a promising class of therapeutics.
Cent Eur J Biol 2: 1–33.- For example, bacterial proteins are special in containing formylated methi-
onine on one end. Bacterial DNA differs from animal DNA in being rich in
unmethylated “CpG motif.” Besides, bacteria possess cell walls and flagella,
which are absent in animals. Components of bacterial cell walls such as
peptidoglycan, lipopolysaccharide (LPS), and teichoic acid, and molecules
unique to fungal cell walls such as mannan, glucan and chitin, are recog-
nized by animal cells as non-self. - Sun L, Wu J, Du F, et al. (2013) Cyclic GMP-AMP synthase is a cytosolic
DNA sensor that activates the type I interferon pathway. Science 339:
786–791. - Both B and T lymphocytes originate in the bone marrow, but T cells, in
addition, have to pass through the thymus to reach maturity, hence the
name “T”. - There are two types of MHC: MHC-I and MHC-II. Whereas MHC-II
is found only in specialized antigen presenting cells (such as dendritic
cells), MHC-I is present on the surface of all cells except red blood cells.
MHC-I is the one that is relevant in recognition of self during organ or tissue
transplantation. Since each individual has a unique MHC-I, transplantation
of organs or tissue from one person to another triggers T cell-mediated
immune rejection by the host. The individual difference in MHC-I is due
to variation in amino acid sequence of the protein, a phenomenon called
genetic polymorphism. - Donelson JE. (2003) Antigenic variation and the African trypanosome
genome. Acta Tropica 85: 391–404. - Ljunggren H-G, Kärre K. (1990) In search of the “missing self”: MHC mol-
ecules and NK cell recognition. Immunology Today 11: 237–244. - For general references for this chapter, see the following: Alberts B, et al.
(2008) Molecular Biology of the Cell. 5th ed. Garland Science, New York;
Murphy K. (2012) Janeway’s Immunobiology. 8th ed. Garland Science,
New York; Parham P. (2009) The Immune System. 3rd ed. Garland Science,
New York. - Roitt IM. (1988) Essential Immunology. 6 th ed. Blackwell Mosby, Oxford, UK.