Collagen, the protein that builds skin, bones, tendons and organs, exists inside cells as a liquidlike droplet rather than the long, rigid rod seen in textbooks over the last half-century, according to a new study from the Center for Genomic Regulation (CRG) in Barcelona.

The finding, published in the Journal of Cell Biology, is the first direct observation of how the most abundant protein in the human body, which accounts for around a third of total protein mass, exists naturally inside living cells.

“Inside a cell, collagens are not rigid molecules as one had assumed. They are in fact very pliable, taking a liquid condensate form much like oil in a drop of water,” explains ICREA Research Professor Vivek Malhotra, senior author of the study at the CRG in Barcelona.