triplexes

Triplexes refer to structures or constructs composed of three parts. The term is used in several fields with different meanings, most commonly in real estate and in molecular biology. Although the two usages share etymology, they describe distinct concepts: one describes a type of building arrangement, the other a form of nucleic acid interaction.

In housing, a triplex is a residential building containing three separate housing units. It can be configured as three stacked units within a single building, or as three attached units sharing walls. Each unit may have its own entrance; ownership structure varies: a single owner with all three units, or separate owners in a condominium or cooperative arrangement. Common layouts include three levels with separate access or a central corridor. Triplexes are valued for efficient land use and potential rental income, but can pose management challenges, shared maintenance, and financing or zoning considerations.

In molecular biology, triplex DNA refers to triple-stranded DNA formed when a third strand binds to a double-stranded segment through Hoogsteen hydrogen bonds. Triplexes can be sequence-specific and are favored under certain pH and ionic conditions. They are mainly studied as tools for gene regulation, genome targeting, or therapeutic approaches using triplex-forming oligonucleotides. In normal physiological conditions, triplex structures are relatively rare, and their stability and safety are active areas of research.