Question

help wsecond typed question

Monocytes move from the systemic circulatory system into general connective tissues, where they differentiate into what phagocytic cell type?

V(D)J recombination of germline encoded variable genes is required to produce the near limitless specificities or lymphocyte abtigen receptors. name the enzyme/enzymes that are responsible for initiating V(D)J recombination by recognizing sequences of 12 and 23 base pairs

Answer 1

The important enzymes involved are recombination activating genes 1 and 2 (RAG), terminal deoxynucleotidyl transferase (TdT), and Artemis nuclease, a member of the ubiquitous non-homologous end joining (NHEJ) pathway for DNA repair.

Recombination Activation enzymes initiate rearrangement and recombination of genes of immunoglobulin and T cell receptor. There are two types of RAG found in lymphocytes , RAG1 and RAG2 which are essential for generation of mature B and T cell. They recognise RSS signal present on the gene and cleave the non coding region of DNA between the two exons to be joined. Their absence can lead to severe immunodeficiencies like SCID

Other enzymes are involved in the process are DNA-dependent protein kinase (DNA-PK), X-ray repair cross-complementing protein 4 (XRCC4), DNA ligase IV, non-homologous end-joining factor 1 (NHEJ1) for joining two sequences after recombination by RAG.