important processes to memorize

V(D) J redomb

rss (signla sequence) : flank Ig gene segemtn and guide recomb

rag 1 and rag 2: cut DNA at the rss and bring the gene segments together to form one fucitnal gene

vdj light comb formation

v and j gene segment in genomic dna are joined to form VL exon

the light chain c regoin is encoded in seperate exon and joined to VL econ by splicing of light chain rna

the leader peptide directs protein into cell secrtaory pathway and cleaved

heavy chain

d and j gene sgement join, then v gene segment joins to dj sequence, forms VH exon

heavy chain c region encoded by exons, c region exon joined to vh evon by spolicng of heavy chain RNA

then leader peptide directs prtoein cell sectraory pathway and then cleaved

how are peptides processed and loaded onto MHC class 1

• Proteins in cytosol → broken into peptides (proteasome)

• Peptides transported to ER by TAP

• Calnexin, calreticulin, ERp57, tapasin help fold MHC I + bring it near TAP

• Peptides loaded onto MHC I in peptide-loading complex

• Complex helps proper assembly + peptide binding

How are peptides processed and loaded onto MHC class II?

• Extracellular proteins → taken into acidified vesicles → broken into peptides

• Invariant chain guides MHC II to vesicles

• CLIP blocks binding site initially

• HLA-DM removes CLIP → allows peptide to bind

• Peptide-loaded MHC II → presented on cell surface