Experiment on Direct Mutagenesis using PCR Literature Term Paper (Term Paper Sample)

Name:
Institution Affiliation:
Date:
Introduction
Arabidopsis response regulator 6
Arabidopsis thaliana response regulators (ARRs) are a group of proteins that are involved in the phytohormones cytokinin signaling in this plant. These proteins are uniquely grouped together by having a conserved aspartate (Asp) that serves as the phosphorylation site (To et al., 2007). At present, 32 genes have been isolated and characterized to encode both positive and negative Arabidopsis response regulators (Schaller et al., 2008). Protein domain structure prediction and amino acid sequence analysis has over the past few years enabled categorization of these proteins into three discrete sub-families – type-A, type-B and pseudoregulators (Hwang et al., 2002).
The domain families represented by these groups are linked to the functions of these response regulators. Type-A ARRs harbors only the receiver domain, type-B contains the same receiver domain fused to the DND-binding domain while the pseudoregulators harbors an irregular receiver domain lacking in the conserved D-D-K (Asp-Asp-Lys) motifs characteristic of the receiver domain (Hwang et al., 2002).
ARR6 belongs to the A. thaliana type-A response regulators sub-family that comprises of seven members (ARR3 – 9) involved in phosphoaccepting response regulation. This sub-family has recently grown in number to include four additional response regulators ARR15 – 17 and ARR22 identified from Arabidopsis EST and genomic database (Imamura et al., 1998). Type-A ARRs primarily comprises of a receiver domain, short terminal extensions on the C- and N- ends, and characteristically lacks any distinctive output domain. Type-A ARR genes have been characterized as the basal cytokinin response targets playing primary roles in cytokinin signaling (Kiba et al., 1999). Particularly, ARR6 works to render a negative feedback mechanism by suppressing the cytokinin-responsive ARR6 promoter during cytokinin signaling in Arabidopsis (Hwang and Sheen, 2001).