250 - Adipocyte-enhancer binding unit 1

Abstract

Publisher Summary This chapter examines the structural chemistry and the biological aspects of adipocyte-enhancer binding unit 1 (AEBP1). AEBP1 is a transcription factor with carboxypeptidase (CP) activity that is vital for transcriptional repression function. Sequence comparisons and kinetic studies have characterized AEBP1 as a member of the regulatory B-like CP or metallocarboxypeptidase gene family. This type of CP plays an important role in the processing of active peptides, alteration of receptor specificity for substrates and the termination of polypeptide activity. His-tagged recombinant AEBP1 is capable of cleaving the synthetic substrates hippuryl-arginine and hippuryl-lysine, but not hippuryl-phenylalanine, indicating that AEBP1 functions similarly to these regulatory B-like enzymes. Its target DNA, the AE-1 oligonucleotide, can also enhance the enzymatic activity of AEBP1. The inherent CP activity of AEBP1, which is stimulated by binding to the AE-1 sequence, may be required for AEBP1 to repress transcription of the aP2 gene by an active repression mechanism. His-tagged recombinant AEBPl has been purified and shown to be functional in terms of CP, transcriptional and DNA-binding activities. Only a baseline level of activity is observed when cell homogenates containing baculovirus-expressed AEBPl is tested for CP activity using Dns-Phe-Ala-Arg as a substrate.