Info

Fig. 1. The HLA complex present on human chromosome 6, can be subdivided into three regions. The genes present in each region encode class I, class III, and class II molecules, respectively. The class II region, which is closest to the centromere of the chromosome, is conventionally subdivided into three additional subregions. Among the genes contained in each subregion are some that encode functional molecules (in black), genes that are not functioning (i.e., pseudogenes) (in white), or genes that encode proteins not yet characterized (also in white). Although DQA1 and DQB1 genes encode for the a- and P-chains of a functional HLA-DQ molecule (like DPA1 and DPB1 genes for the chains of a functional HLA-DP molecule), the DRA1 gene encodes for a nonpolymorphic a-chain able to pair with the products of each of the functional DRB genes. In the example, a DR3-positive haplotype of an individual is shown. The DRB1 gene encodes for the DR3 allele, DRB2 is a pseudogene, and DRB3 encodes for the so-called DR52 molecule, which is always found associated with DR3. The DRB9 gene has not been well studied yet but seems to be able to encode for a nonfunctionally stable protein chain. Transporter associated with antigen processing (TAP) 1 and 2 genes are cytoplasmic transporters of antigenic peptides, whereas LMP 2 and 7 are genes encoding proteasome subunits. Both of these molecules are involved in the antigenic peptide transport from the cytoplasm to the cell surface. Tumor necrosis factor (TNF)-a and TNF-P genes, located between class I and class III regions, are also indicated. The 21-hydroxylase locus encompassing CYP21P and CYP21 genes is simply indicated as "21". (Modified from ref. 192.)

Table 5

Comparison Between Class I and Class II Molecules

Table 5

Comparison Between Class I and Class II Molecules

Was this article helpful?

0 0
Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

Get My Free Ebook


Post a comment