PubMed HealthSearch

PubMed · 163073

Cellular structure and function in normal and neoplastic lymphoid cells.

Abstract

In general, the ultrastructure of normal lymphocytes and plasma cells reflects their functional state. Similarly, in pathologic conditions, ultrastructural abnormalities may reflect specific functional derangements of the cells. The identification of some structural abnormalities may be clinically useful, even though their origin and biochemical composition is still obscure.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

D Zucker-Franklin. 1975. Cellular structure and function in normal and neoplastic lymphoid cells.. https://pubmed.ncbi.nlm.nih.gov/163073/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

The cell-cycle regulated transcription factor B-Myb is phosphorylated by cyclin A/Cdk2 at sites that enhance its transactivation properties.

Expression of the B-Myb transcription factor is upregulated during late G1 phase of the cell cycle by an E2F-dependent transcriptional mechanism. B-Myb is specifically phosphorylated during S phase, suggesting that a cyclin-dependent kinase (Cdk) regulates its activity. Consistent with this notion, the S phase-specific cyclin A/Cdk2 was found previously to enhance B-Myb transactivation activity in cotransfected cells. In this study we provide evidence that B-Myb is a direct physiological target for cyclin A/Cdk2. We demonstrate that B-Myb is an in vitro substrate for cyclin A/Cdk2, but not for cyclin D1/Cdk4 or cyclin E/Cdk2. By mutating candidate Cdk2 phosphorylation sites, we show that B-Myb is phosphorylated at Thr447, Thr490, Thr497 and Ser581 by cyclin A/Cdk2 in vitro and that these sites are also phosphorylated in cycling U-2 OS cells. Inhibition of endogenous Cdk2 by dominant negative Cdk2 attenuated phosphorylation of Thr447, Thr490 and Thr497, but had no effect upon Ser581 modification. B-Myb transactivation activity was significantly reduced in a mutant containing amino acid substitutions at all four identified cyclin A/Cdk2 sites and was constitutively low in Saos-2 cells where endogenous cyclin A/Cdk2 activity was unable to phosphorylate ectopically expressed B-Myb. These data indicate that phosphorylation by cyclin A/Cdk2 is directly involved in enhancing B-Myb transactivation activity and that levels of endogenous cyclin A/Cdk2 activity may contribute to cell line-specific B-Myb function.

Bone Neoplasms