CUL4B Antibody – Rabbit Polyclonal

This gene is a member of the cullin family. The encoded protein forms a complex that functions as an E3 ubiquitin ligase and catalyzes the polyubiquitination of specific protein substrates in the cell. The protein interacts with a ring finger protein, and is required for the proteolysis of several regulators of DNA replication including chromatin licensing and DNA replication factor 1 and cyclin E. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

CUL4B iso1: Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. The functional specificity of the E3 ubiquitin-protein ligase complex depends on the variable substrate recognition subunit. CUL4B may act within the complex as a scaffold protein, contributing to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. Plays a role as part of the E3 ubiquitin-protein ligase complex in polyubiquitination of CDT1, histone H2A, histone H3 and histone H4 in response to radiation- induced DNA damage. Targeted to UV damaged chromatin by DDB2 and may be important for DNA repair and DNA replication. Required for ubiquitination of cyclin E, and consequently, normal G1 cell cycle progression. Regulates the mammalian target-of-rapamycin (mTOR) pathway involved in control of cell growth, size and metabolism. Specific CUL4B regulation of the mTORC1-mediated pathway is dependent upon 26S proteasome function and requires interaction between CUL4B and MLST8. Defects in CUL4B are the cause of mental retardation syndromic X-linked Cabezas type (MRXC); also known as mental retardation syndromic X-linked type 15. A syndromic form of X-linked mental retardation characterized by severe intellectual deficit associated with short stature, craniofacial dysmorphism, small testes, muscle wasting in lower legs, kyphosis, joint hyperextensibility, pes cavus, small feet, and abnormalities of the toes. Additional neurologic manifestations include speech delay and impairment, tremor, seizures, gait ataxia, hyperactivity and decreased attention span. Belongs to the cullin family. 3 isoforms of the human protein are produced by alternative splicing.

Protein type: Cell cycle regulation

Chromosomal Location of Human Ortholog: Xq23

Cellular Component: nucleoplasm; cytoplasm; plasma membrane

Molecular Function: protein binding; ubiquitin protein ligase binding; damaged DNA binding

Biological Process: ubiquitin-dependent protein catabolic process; positive regulation of protein catabolic process; cell cycle

Disease: Mental Retardation, X-linked, With Short Stature, Hypogonadism, And Abnormal Gait