Gene that produces 38,000 different proteins involved in cellular identification

CAMBRIDGE, Mass. — A single gene that codes for more than 38,000 different proteins may allow individual cells in the brain to distinguish themselves from other cells, says Andrew Chess, a scientist at Whitehead Institute and lead author of the study, which appears online this week in the journal Nature Genetics. Scientists suspect the gene, called Dscam, produces proteins that rest on the surface of neuron cells, prompting a cellular self-awareness that is necessary to ensure the correct wiring of neurons in the brain.

Dscam, part of a family of cell-adhesion molecules, has been shown to produce at least 38,016 different proteins in fruit flies, each with a slightly different structure and function. Although the human Dscam gene produces far fewer proteins, it is implicated in Down syndrome; people with the disease carry an extra copy of chromosome 21, which contains the Dscam gene.

Anxious to study the gene in individual cells, Chess and his research team developed a technique for single-cell analysis in fruit flies that revealed that different individual cells in the brain make different types of Dscam protein.

“This results in every cell containing a Dscam repertoire that is different from those of its neighbors,” says Chess, who also is an associate professor of biology at Massachusetts Institute of Technology.