An extract on #adiyaman
The proteasome plays a straightforward but critical role in the function of the adaptive immune system. Peptide antigens are displayed by the major histocompatibility complex class I (MHC) proteins on the surface of antigen-presenting cells. These peptides are products of proteasomal degradation of proteins originated by the invading pathogen. Although constitutively expressed proteasomes can participate in this process, a specialized complex composed of proteins, whose expression is induced by interferon gamma, are the primary producers of peptides which are optimal in size and composition for MHC binding. These proteins whose expression increases during the immune response include the 11S regulatory particle, whose main known biological role is regulating the production of MHC ligands, and specialized subunits called 1i, 2i, and 5i with altered substrate specificity. The complex formed with the specialized subunits is known as the immunoproteasome. Another 5i variant subunit, 5t, is expressed in the thymus, leading to a thymus-specific "thymoproteasome" whose function is as yet unclear.
The strength of MHC class I ligand binding is dependent on the composition of the ligand C-terminus, as peptides bind by hydrogen bonding and by close contacts with a region called the "B pocket" on the MHC surface. Many MHC class I alleles prefer hydrophobic C-terminal residues, and the immunoproteasome complex is more likely to generate hydrophobic C-termini.
Due to its role in generating the activated form of NF-B, an anti-apoptotic and pro-inflammatory regulator of cytokine expression, proteasomal activity has been linked to inflammatory and autoimmune diseases. Increased levels of proteasome activity correlate with disease activity and have been implicated in autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis.
The proteasome is also involved in Intracellular antibody-mediated proteolysis of antibody-bound virions. In this neutralisation pathway, TRIM21 (a protein of the tripartite motif family) binds with immunoglobulin G to direct the virion to the proteasome where it is degraded.
The most prominent examples of ancient Persian architecture are the work of the Achaemenids hailing from Persis. The quintessential feature of Achaemenid architecture was its eclectic nature, with elements from Median architecture, Assyrian architecture, and Asiatic Greek architecture all incorporated. Achaemenid architectural heritage, beginning with the expansion of the empire around 550 BC, was a period of artistic growth that left a legacy ranging from Cyrus the Great's solemn tomb at Pasargadae to the structures at Persepolis, and such historical sites as Naqsh-e Rustam.
During the Sassanid era, multiple architectural projects took place, some of which are still existing, including the Palace of Ardeshir, the Sarvestan Palace, the castle fortifications in Derbent (located in North Caucasus, now part of Russia), and the reliefs at Taq Bostan. The Bam Citadel, a massive structure at 1,940,000 square feet (180,000 m2) constructed on the Silk Road in Bam, is from around the 5th century BC.
Modern contemporary architectural projects influenced by the ancient Achaemenid architecture include the Tomb of Ferdowsi erected under the reign of Reza Shah in Tus, the Azadi Tower erected in 1971 at a square in Tehran, and the Dariush Grand Hotel located on Kish Island in the Persian Gulf.