componentsSkp1

componentsSkp1 is a term used to describe the Skp1 components within the Skp1-Cullin-F-box (SCF) ubiquitin ligase family. Skp1, or S-phase kinase-associated protein 1, acts as an adaptor that links substrate-recognition F-box proteins to the Cullin-1 scaffold, enabling ubiquitination of target proteins and their degradation by the proteasome. The concept is used to refer to the Skp1 subunit and its interacting partners as a functional module in eukaryotic cells.

Structure and interactions: In most organisms, the SCF core consists of Skp1, Cullin-1, and Rbx1, with a variable F-box protein determining substrate specificity. Skp1 binds the F-box domain of the receptor protein, while Cullin-1 provides a scaffold for assembling Rbx1 and the E2-conjugating enzyme. Skp1 sequences are conserved, yet many lineages show diversification of Skp1-like proteins, which can influence complex assembly and substrate range.

Biological role: The SCF complex mediates ubiquitination of a broad set of substrates involved in cell cycle control, development, and signaling. Its modular design allows different F-box proteins to recruit distinct substrates, while Skp1 serves as a critical linker that promotes proper assembly and activity of the ligase.

Evolution and variation: Yeast typically harbor a single Skp1 gene, whereas plants and some animals possess Skp1-related families with multiple paralogs. Plant SKP1-like proteins often participate in diverse pathways and can interact with several F-box partners, illustrating functional redundancy and specialization within the componentsSkp1 group.

See also: ubiquitin-proteasome system, SCF complex, F-box proteins, Cullin-RING ligases.