Puralpha: a multifunctional single-stranded DNA- and RNA-binding protein.
Puralpha is a ubiquitous, sequence-specific DNA- and RNA-binding protein which is highly conserved in eukaryotic cells. Puralpha has been implicated in diverse cellular functions, including transcriptional activation and repression, translation and cell growth. Moreover, this protein has been shown to be involved in regulating several human viruses which replicate in the central nervous system (CNS), including human immunodeficiency virus type I (HIV-1) and JC virus (JCV). Puralpha exerts part of its activity by interacting with cellular proteins, including pRb, E2F, cyclin A, Sp1 and members of the Y-box family of proteins, including YB-1 and MSY1, as well as viral proteins such as polyomavirus large T-antigen and HIV-1 Tat. The ability of Puralpha to interact with its target DNA sequence and to associate with several viral and cellular proteins is modulated by RNA. Puralpha has also been shown to be involved in cell growth and proliferation. Its association with pRb, E2F and cyclin A coupled with its fluctuating levels throughout the cell cycle, position Puralpha as a crucial factor in the cell cycle. Moreover, microinjection studies demonstrate that Puralpha causes either a G(1) or G(2) arrest depending on the cell cycle time of injection. The gene encoding Puralpha has been localized to a human locus which is frequently deleted in myelogenous leukemias and other cancers and Puralpha gene deletions have been detected in many cases of lymphoid cancers. The following review details the structural characteristics of Puralpha, its family members and the involvement of this protein in regulating various cellular and viral genes, viral replication and cell growth.
Gallia
G L
GL
Center for NeuroVirology and Cancer Biology, Laboratory of Molecular NeuroVirology, College of Science and Technology, Temple University, 1900 North 12th Street, 015-96, Room 203, Philadelphia, PA 19122, USA.
Johnson
E M
EM
Khalili
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000235:genetics
D017362:Cyclic AMP Response Element-Binding Protein; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C501130:PURA protein, human; D016601:RNA-Binding Proteins; D014157:Transcription Factors