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. Author manuscript; available in PMC: 2013 Jul 31.
Published in final edited form as: Cell. 2013 Jan 31;152(3):394–405. doi: 10.1016/j.cell.2012.11.043

Figure 5. Consequences of changes in gene copy number.

Figure 5

(A) An increased dosage of a single gene, such as a rate-limiting enzyme B, can increase the output or function of a cellular pathway. Conversely, reduction of enzyme B will diminish the production of C thus decreasing pathway activity.

(B) Altered gene dosage can interfere with the function of stoichiometry-sensitive complexes, with excess of protein A or protein B inhibiting the function of C and therefore decreasing pathway activity.

(C) Overexpression of a regulatory enzyme can lead to off-target effects. For example overexpression of a protein kinase or protein phosphatase can cause deregulation of pathways that proteins usually do not function in.

(D) Changes in the copy number of many genes simultaneously can impact protein quality control mechanisms such as molecular chaperones and the ubiquitin–proteasome system (UPS). Misfolded proteins can eventually form aggregates.