Cycline1 (CCNE1) Recombinant Protein

The protein encoded by this gene belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance through the cell cycle. Cyclins function as regulators of CDK kinases. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event. This cyclin forms a complex with and functions as a regulatory subunit of CDK2, whose activity is required for cell cycle G1/S transition. This protein accumulates at the G1-S phase boundary and is degraded as cells progress through S phase. Overexpression of this gene has been observed in many tumors, which results in chromosome instability, and thus may contribute to tumorigenesis. This protein was found to associate with, and be involved in, the phosphorylation of NPAT protein (nuclear protein mapped to the ATM locus), which participates in cell-cycle regulated histone gene expression and plays a critical role in promoting cell-cycle progression in the absence of pRB. Two alternatively spliced transcript variants of this gene, which encode distinct isoforms, have been described. Two additional splice variants were reported but detailed nucleotide sequence information is not yet available. [provided by RefSeq, Jul 2008]

Function: Essential for the control of the cell cycle at the G1/S (start) transition. Ref.3

Subunit structure: Interacts with a member of the CDK2/CDK protein kinases to form a serine/threonine kinase holoenzyme complex. The cyclin subunit imparts substrate specificity to the complex. Found in a complex with CDK2, CABLES1 and CCNA1

By similarity. Part of a complex consisting of UHRF2, CDK2 and CCNE1. Interacts directly with UHRF2; the interaction ubiquitinates CCNE1 and appears to occur independently of CCNE1 phosphorylation. Ref.13 Ref.17

Subcellular location: Nucleus Ref.3.

Tissue specificity: Highly expressed in testis and placenta. Low levels in bronchial epithelial cells. Ref.11

Post-translational modification: Phosphorylation of both Thr-395 by GSK3 and Ser-399 by CDK2 creates a high affinity degron recognized by FBXW7, and accelerates degradation via the ubiquitin proteasome pathway. Phosphorylation at Thr-77 creates a low affinity degron also recognized by FBXW7.Ubiquitinated by UHRF2; appears to occur independently of phosphorylation. Ref.17

Sequence similarities: Belongs to the cyclin family. Cyclin E subfamily.