DP-2, a heterodimeric partner of E2F: identification and characterization of DP-2 proteins expressed in vivo.
E2F is a heterodimeric transcription factor that regulates the expression of genes at the G1/S boundary and is composed of two related but distinct families of proteins, E2F and DP. E2F/DP heterodimers form complexes with the retinoblastoma (Rb) protein, the Rb-related proteins p107 and p130, and cyclins/cdks in a cell cycle-dependent fashion in vivo. E2F is encoded by at least five closely related genes, E2F-1 through -5. Here we report studies of DP-2, the second member of the DP family of genes. Our results indicate that (i) DP-2 encodes at least five distinct mRNAs, (ii) a site of alternative splicing occurs within the 5' untranslated region of DP-2 mRNA, (iii) at least three DP-2-related proteins (of 55, 48, and 43 kDa) are expressed in vivo, (iv) each of these proteins is phosphorylated, and (v) one DP-2 protein (43 kDa) carries a truncated amino terminus. Our data also strongly suggest that the 55-kDa DP-2-related protein is a novel DP-2 isoform that results from alternative splicing. Thus, we conclude that DP-2 encodes a set of structurally, and perhaps functionally, distinct proteins in vivo.
Rogers
K T
KT
Department of Molecular Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
Higgins
P D
PD
Milla
M M
MM
Phillips
R S
RS
Horowitz
J M
JM
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002460:Cell Line; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D004591:Electrophoresis, Polyacrylamide Gel; D018257:Helix-Loop-Helix Motifs; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D005810:Multigene Family; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D056465:Retinoblastoma-Binding Protein 1; D012441:Saccharomyces cerevisiae; D012689:Sequence Homology, Nucleic Acid; D013462:Sulfur Radioisotopes; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D010710:Phosphates; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D013462:Sulfur Radioisotopes; D050680:Transcription Factor DP1; D014157:Transcription Factors; D008715:Methionine