IMMUNOLOGY

Bios 328a textbook-based study of immunologySpring 2003

http://www.lehigh.edu/~sk08/Courses/Bios328/mainpage.htm

TCR (seen here in a ternary complex…)

TCR (seen here in a ternary complex…)

TCR’s come in two flavors…

TCR’s (like Ig’s) have immense diversity

TCR’s (like Ig’s) have immense diversity

5461 ?????????

40 + 41 + 42 + 43 + 44 + 45 + 46 = 5461

40 + 41 + 42 + 43 + 44 + 45 + 46 = 5461

(22)0 + (22)1 + (22)2 + (22)3 + (22)4 + (22)5 + (22)6 = 5461

20 + 22 + 24 + 26 + 28 + 210 + 212 = 5461

“CD3”

two heterodimers &one homodimer…

specifically:

(a variant… is

obtained by alternative splicing of the template)

“CD3”All of the CD3 proteins

have a negative charge (aspartic acid) in the transmembrane helix. Interacts with positive charge in the TCR transmembrane component.

All CD3 proteins have ITAM (immunoreceptor tyrosine activation motifs) recognized by

tyrosine kinases. (Members of the larger MIRR [multi chain immune recognition receptor] class.)

“CD3”gamma, delta, and

epsilon are members of the immunoglobulin superfamily. Each chain has an immunoglobulin domain + a transmembrane component + a cytoplasmic tail (approximately 44 to 55 amino acids long)

90% of chains with zeta are homodimers. Zeta and eta have 9 aa external domains, a transmembrane component and a cytoplasmic tail of 113 aa in zeta and 155 aa in eta; the two variants are transcripts of a common gene; the transcripts are alternatively spliced.

CD 4 & CD8

A heterodimer(usually sometimes )

One immunoglobulin domain

“small” glycoproteins(30 – 38 kDa)

-S—S-

+ transmembrane component

+ cytoplasmic tail (25-27 residues)

55 kDa monomeric glycoprotein

Four immunoglobulin domains

+

a transmembrane component

+a long cytoplasmic domain (with three serine residues)

CD4 and MHC-II

The length of immunoglobulin folds in CD4 is equal to the two immunoglobulin folds in a TCR plus the peptide binding domain in MHC-II and the proximal immunoglobulin fold in MHC-II.

Thus, these components can associate. Specifically, the most distal immunoglobulin fold of CD4 associates with the 2 immunoglobulin fold of MHC-II.

CD4 and MHC-II

Other moleculesLots of them… and, they’re important too!

Other molecules