TABLE 1.

Comparison of functional capabilities shown quantitatively for different regulatory network motifs

Functional capabilities	Bifan (this study)	Feed forward loop	Feedback loop	SIM
Delay/speedup	Depends on logical gating	Exact function depends on sign, logical gating, and coherence (8,13,15,23)	Autoregulation may reduce response time whereas longer loops can cause delay (14,32)
Filter noise	AND gates filter better than OR gates	FFLs reject transient input pulses and respond only to persistent stimuli (16,24)	Filtering by using interlinked loops (28)
Sort and synchronization	TF activity is synchronized under a broad range of conditions			Input node is often autoregulated, yielding a coupling between a FBL and a SIM (13,14)
Bistability			Fluctuations and stochasticity play a role in switching between the stable states (17,19,20,25–27)
Oscillations			Negative feedback is required for oscillations (12,17,18,28–31)

FBL, feedback loop; FFL, feed forward loop; SIM, single input modules; TF, transcription factor.