- b-cells (bone marrow) has antibodies that bind antigens, then it makes clones of these b-cell types and the clones secrete antibodies into the blood stream, eg IgG, IgM (pentamer) (Y structure)
- t-cells 'killer' (thymus) has t-cell receptors which also has immnuglobulin (antibody) folds that recognizes antigens that are bound to mhc complex of infected cells (U structure only)
IgG (humoral, B-cell antibodies):
- immunoglobulin fold has 4 chains, 2 light and 2 heavy chains, 2 anti-parallel beta sheets packed against each other forming a barrel
- fc = crystalizable fragment, fab - antigen binding fragment
- fc and fab connected together by hinge region / flexible linker
- constant domain (ch1, cl) - 4+3 beta strand connected by short loops, linked by disulfide bonds, sheets are 90 degrees, hydrophobic interactions, 4 strands (longest sheet) in the middle, 3 strands in the outside
- variable domain (vh and vl) - 4+3+2 beta strand, long loops for antigen binding, cdr1-3 (complementarityy determining region) or hypervariable region on the same side, c' and c'' forms cdr2, cdr1 connects sheet 1 and 2 (crossover turn), cdr3 has the most variability, 5 strands in the middle (longest sheet) and 4 strands on the outside, c" not involved in packing (outside the barrel)
- epitope (Antigenic determinants) - part of antigen recognized by antibody (vs paratope - part of antibody recognize epitope)
T-Cell Receptors:
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