B7

B7, B.VII or B-7 may refer to:

Vehicles and transportation

In science

Other

List of bus routes in Brooklyn

The Metropolitan Transportation Authority (MTA) operates a number of bus routes in Brooklyn, New York, United States; one minor route is privately operated under a city franchise. Many of them are the direct descendants of streetcar lines (see list of streetcar lines in Brooklyn); the ones that started out as bus routes were almost all operated by the Brooklyn Bus Corporation, a subsidiary of the Brooklyn–Manhattan Transit Corporation, until the New York City Board of Transportation took over on June 5, 1940. Of the 55 local Brooklyn routes operated by the New York City Transit Authority, roughly 35 are the direct descendants of one or more streetcar lines, and most of the others were introduced in full or in part as new bus routes by the 1930s. Only the eastern section of the B82 (then the B50), the B83, and the B84 were created by New York City Transit from scratch, in 1978, 1966, and 2013, respectively.

List of routes

This table gives details for the routes prefixed with "B" - in other words, those considered to run primarily in Brooklyn by the MTA. For details on routes with other prefixes, see the following articles:

B7 (protein)

B7 is a type of peripheral membrane protein found on activated antigen presenting cells (APC) that, when paired with either a CD28 or CD152 (CTLA-4) surface protein on a T cell, can produce a costimulatory signal or a coinhibitory signal to enhance or decrease the activity of a MHC-TCR signal between the APC and the T cell, respectively. Besides being present on activated APCs, B7 is also found on T-cells themselves.

Binding of the B7 on T-cells to CTLA-4 causes inhibition of the activity of T-cells.

There are two major types of B7 proteins: B7-1 or CD80, and B7-2 or CD86. However, it is not known if they differ significantly from each other. CD28 and CTLA-4 each interact with both B7-1 and B7-2.

Costimulation

There are several steps to activation of the immune system against a pathogen. The T cell receptor must first interact with the Major histocompatibility complex (MHC) surface protein. The CD4 or CD8 proteins on the T-cell surface form a complex with the CD3 protein, which can then recognize the MHC. This is also called "Signal 1" and its main purpose is to guarantee antigen specificity of the T cell activation.