PlayStation Network (PSN) is an entertainment service provided by Sony Network Entertainment International for use with the PlayStation family of video game consoles, Sony tablets, smartphones, Blu-ray players and HDTVs. The PlayStation Network encompasses online gaming, music, television and movie streaming services.

History

Launched in the year 2000, Sony's second home console, the PlayStation 2, had a limited number of online features in select games via its online network. It required a network adaptor, which was available as an add-on for original models and integrated into the hardware on slimline models. However, Sony provided no unified service for the system, so support for network features was specific to each game and there was no interoperability of cross-game presence. Five years later, during the development stage for its third home console, the PlayStation 3, Sony expressed their intent to build upon the functionality of its predecessor by creating a new interconnected service that keeps users constantly in touch with a "PlayStation World" network." In March 2006, Sony officially introduced its unified online service, tentatively named "PlayStation Network Platform". A list of supporting features was announced at the Tokyo Game Show later the same year.

PSN is the PlayStation Network, an online service for Sony PlayStation game consoles. It can also refer to PlayStation Now, a streaming games service for PlayStation consoles, televisions, and mobile devices.

PSN may also refer to:

Computing

Transport

Politics

Other uses

Presenilins are a family of related multi-pass transmembrane proteins which constitute the catalytic subunits of the gamma-secretase intramembrane protease complex. They were first identified in screens for mutations causing early onset forms of familial Alzheimer's Disease by Peter St George-Hyslop at the Centre for Research in Neurodegenerative Diseases at the University of Toronto, and now also at the University of Cambridge. Vertebrates have two presenilin genes, called PSEN1 (located on chromosome 14 in humans) that encodes presenilin 1 (PS-1) and PSEN2 (on chromosome 1 in humans) that codes for presenilin 2 (PS-2). Both genes show conservation between species, with little difference between rat and human presenilins. The nematode worm C. elegans has two genes that resemble the presenilins and appear to be functionally similar, sel-12 and hop-1.

Presenilins undergo cleavage in an alpha helical region of one of the cytoplasmic loops to produce a large N-terminal and a smaller C-terminal fragment that together form part of the functional protein. Cleavage of presenilin 1 can be prevented by a mutation that causes the loss of exon 9, and results in loss of function. Presenilins play a key role in the modulation of intracellular Ca²⁺ involved in presynaptic neurotransmitter release and long-term potentiation induction.