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Updated: Feb 1, 2026

Rapid Characterization of Genetic Parts with Cell-Free Systems
Published on: August 30, 2021
Planar cell polarity: two genetic systems use one mechanism to read gradients
Peter A Lawrence1, José Casal2
1Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK pal38@cam.ac.uk.
Abstract:
Our aim in this short Primer is to explain the principles of planar cell polarity (PCP) in animal development. The literature in this small field is complex and specialized, but we have extracted a simple and central story from it. We explain our hypothesis that polarity, initially cued by the direction of slope of a multicellular gradient, is interpreted at the cellular level so that each cell becomes molecularly polarised. The mechanism involves a comparison between a cell and its neighbours. To achieve this comparison there are (at least) two disparate and independent molecular systems, each depending on molecular bridges that span between neighbouring cells. Even though the two systems are made up of different molecules, we argue that both systems function in a logically equivalent way.
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