Brown SA Kowalska E Dallmann R 2012 For 20 years, researchers have thought that circadian clocks are defined by feedback loops of transcription and translation. The rediscovery of posttranslational circadian oscillators in diverse organisms forces us to rethink this paradigm. Meanwhile, the original "basic" feedback loops of canonical circadian clocks have swelled to include dozens of additional proteins acting in interlocked loops. We review several self-sustained clock mechanisms and propose that minimum requirements for diurnal timekeeping might be simpler than those of actual free-running circadian oscillators. Thus, complex mechanisms of circadian timekeeping might have evolved from random connections between unrelated feedback loops with independent but limited time-telling capability. application/pdf https://sonar.ch/global/documents/160807 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.devcel.2012.02.007 info:eu-repo/semantics/altIdentifier/pmid/22421040 info:eu-repo/semantics/openAccess Developmental cell. - 2012 Animals Biological Clocks CLOCK Proteins Circadian Rhythm Drosophila Drosophila Proteins Humans Protein Processing, Post-Translational Transcription, Genetic (Re)inventing the circadian feedback loop. http://purl.org/coar/resource_type/c_6501