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UBCA gene on chromosome 12q24.3 that encodes ubiquitin C, which plays different roles depending on which lysine residue is covalently bound to what protein. Ubiquitins are either covalently attached to another protein, or free (unanchored). When covalently bound, ubiquitin is conjugated to target proteins, either as a monomer (monoubiquitin), a polymer linked to different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chain). Polyubiquitin chains attached to a target protein have different functions depending on the Lys residue of the ubiquitin attached. Linear polymer chains formed by attaching to the initiator Met lead to cell signalling. Free (unanchored) polyubiquitin is involved in activating protein kinases and in signalling.
UBC is also a less preferred gene symbol for what is now designated as UBB, see there.
Ubiquitin activities—Lys binding
• Lys-6-linked—DNA repair
• Lys-11-linked—ERAD (endoplasmic reticulum-associated degradation) and cell-cycle regulation.
• Lys-29-linked—Lysosomal degradation.
• Lys-33-linked—Kinase modification.
• Lys-48-linked—Protein degradation via proteasomes.
• Lys-63-linked—Endocytosis, DNA-damage responses, signalling and activation of transcription factor NF-kappaB.