Pro-interleukin-16 is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the IL16 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

. This gene was discovered in 1982 at Boston University

Boston University

Boston University is a private research university located in Boston, Massachusetts. With more than 4,000 faculty members and more than 31,000 students, Boston University is one of the largest private universities in the United States and one of Boston's largest employers...

 by Dr. David Center and Dr. William Cruikshank.
Interleukin 16 (IL-16) is a cytokine

Cytokine

Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...

 that released by a variety of cells (including lymphocytes and some epithelial cells) that has been characterized as a chemoattractant for certain immune cells expressing the cell surface molecule CD4

CD4

CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

.

IL-16 was originally described as a factor that could attract activated T cells in humans, it was previously called lymphocyte chemoattractant factor (LCF). Since then, this interleukin has been shown to recruit and activate many other cells expressing the CD4 molecule, including monocytes, eosinophils, and dendritic cells.

The structure of IL-16 was determined following its cloning in 1994. This cytokine is produced as a precursor peptide (pro-IL-16) that requires processing by an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 called caspase

Caspase

Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis , necrosis, and inflammation....

-3 to become active. CD4 is the cell signaling

Cell signaling

Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue...

 receptor

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

 for mature IL-16.

Interactions

Interleukin 16 has been shown to interact

Protein-protein interaction

Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...

 with Kir2.1, KCNJ10

KCNJ10

ATP-sensitive inward rectifier potassium channel 10 is a protein that in humans is encoded by the KCNJ10 gene.-SeSAME syndrome:Humans with mutations in the KCNJ10 gene that cause loss of function in related K+ channels can display seizures, sensorineural deafness, ataxia, mental retardation, and...

, GRIN2D

GRIN2D

Glutamate [NMDA] receptor subunit epsilon-4 is a protein that in humans is encoded by the GRIN2D gene.-Interactions:GRIN2D has been shown to interact with Interleukin 16....

, GRIN2A

GRIN2A

Glutamate [NMDA] receptor subunit epsilon-1 is a protein that in humans is encoded by the GRIN2A gene.-Interactions:GRIN2A has been shown to interact with FYN, DLG4, DLG3, DLG1, Src, PTK2B and Interleukin 16.-Further reading:...

, PPP1R12B

PPP1R12B

Protein phosphatase 1 regulatory subunit 12B is an enzyme that in humans is encoded by the PPP1R12B gene.-Interactions:PPP1R12B has been shown to interact with Interleukin 16.-Further reading:...

, PPP1R12A

PPP1R12A

Protein phosphatase 1 regulatory subunit 12A is an enzyme that in humans is encoded by the PPP1R12A gene.-Interactions:PPP1R12A has been shown to interact with Interleukin 16.-External links:* Info with links in the...

 and KCNJ15

KCNJ15

Potassium inwardly-rectifying channel, subfamily J, member 15, also known as KCNJ15 is a human gene, which encodes the Kir4.2 protein.- Function :...

.

Further reading