The marker usually exists as an isodicentric chromosome; i.e. 2 copies of a specific part of the long arm of chromosome 15 (most commonly, 15q11.2-q13.1) that is mirrored and doubled, with 2 centromeres and 2 DNA satellites.
His research contributions include elucidation of the mechanism of genetic missense suppression in bacteria, the development of techniques to make genomic libraries using recombinant DNA, techniques for using yeast for DNA cloning, characterization of centromere DNA, and construction of the first artificial chromosomes.
Shugoshin protein is thought to act by protecting two proteins, named Rec8 and Rad21 at the centromeres from protein degradation by the enzyme, separase.