E2

E2, e2, E02, E.II, e² or E-2 may refer to:

Science and technology

Ubiquitin-conjugating enzyme, a protein component of proteasome-mediated protein degradation
E2 regulatory sequence, for the insulin gene
Levuglandin E2, an aldehyde
Prostaglandin E2, an abortifacient
Prostaglandin E2 receptor, a human gene
Iodine-deficiency (ICD-10 code: E02)
Estradiol, an estrogen steroid hormone
Dihydrolipoyl transacetylase, the second element of the multienzyme pyruvate dehydrogenase complex
Acireductone dioxygenase (iron(II)-requiring), an enzyme
Haplogroup E2 (Y-DNA), a human Y-chromosome DNA haplogroup

E2 (cipher), a block cipher submitted to the AES competition by NTT
Tungsten E2, a business-class Palm OS-based handheld computer
Motorola ROKR E2, a smartphone
Everything2, a collaborative web-based community consisting of a database of interlinked user-submitted written material

"E²", an episode of Star Trek: Enterprise
MTV e2, a Canadian entertainment news program that airs on MTV Canada
E2 (TV channel), a Turkish TV channel
e2 by SKY PerfecTV!, a satellite television service in Japan operated by SKY Perfect

Northrop Grumman E-2 Hawkeye, an American carrier-based AWACS aircraft
Fokker E.II, a 1915 German single-seat monoplane fighter aircraft
Pfalz E.II, a German aircraft powered by the Oberursel U.I engine
Taylor E-2, a small, light and simple utility aircraft
Embraer E-Jet E2 family, an updated version of the E-jet family
Eastman E-2 Sea Rover, a 1920s seaplane
Eurowings Europe (former IATA code: E2), an Austrian airline subsidiary of Lufthansa
Kampuchea Airlines (former IATA code: E2), a Cambodian airline

E2 Series Shinkansen, a Japanese high-speed train
EMC E2, an early American passenger-train diesel locomotive
LB&SCR E2 class, a class of 0-6-0T steam locomotives designed by Lawson Billington
PRR E2, an American PRR 4-4-2 locomotive
CNW Class E-2, a class of 4-6-2 steam locomotives built by the American Locomotive Company in 1923

E02 expressway (Sri Lanka), in Sri Lanka
E2 European long distance path, a long-distance footpath that runs from Galway in Ireland to France's Mediterranean coast
North–South Expressway Southern Route (E2), in Malaysia
European route E002, in Azerbaijan and Armenia
E2 expressway (Philippines), expressway route in the Philippines
San'yō Expressway, Hiroshiwa-Iwakuni Road, Ogori Road and Yamaguchi-Ube Road, numbered as E2 in Japan

E-2 visa, a type of US visa
E2, a postcode district in the E postcode area for east London, England
Private E-2, a pay grade for the rank of Private in the US Army
E2 (nightclub), a nightclub in Chicago, US
Eternity II puzzle, a puzzle competition
E-II Holdings, Inc., an investment holding company formerly owned by Meshulam Riklis, and later by Carl Icahn
E2 grade, an assessment of difficulty in rock climbing