L1 family
Encyclopedia
The L1 family is a family of cell adhesion molecule
s that includes four different L1
-like proteins. They are members of the immunoglobulin superfamily (IgSF CAMs). The members of the L1-family in humans are called L1
or L1cam, CHL1
(close homologue of L1), Neurofascin and NrCAM
(NgCAM related cell adhesion molecule). L1 family members are found on neurons, especially on their axons. Sometimes they are found on glia, such as Schwann cells, radial glia
and Bergmann glia cells and, as such, are important for neural cell migration during development. L1 family members are expressed throughout the vertebrate and invertebrate kingdoms.
L1 family members are able to bind to a number of other proteins. As cell adhesion molecules, they often bind "homophilically" to themselves; for example L1 on one cell binding to L1 on an adjacent cell. L1 family members also bind "heterophilically" to members of the contactin or CNTN1
family. L1 family members bind to many cytoplasmic proteins such as Ankyrin
s, ezrin-moesin-radixin (ERM) proteins, signaling molecules like src (src gene) and erk (Extracellular signal-regulated kinases
) and proteins important in trafficking, such as AP-2.
NrCAM and neurofascin both have class 1 PDZ domain binding motifs at their COOH termini. NrCAM can bind to SAP102 and other members of the MAGUK family.
Roles in the body:
"The importance of L1 in neural development has been revealed in several ways. In humans, mutations in the L1 gene can have devastating consequences. In extreme cases, babies are born with a fatal condition of hydrocephalus
("water on the brain"). Children with less severe mutations typically exhibit mental retardation and difficulty in controlling limb movements (spasticity). Autopsies on patients that have died of an L1-deficiency disease reveal a remarkable condition: they are often missing two large nerve tracts, one that runs in the two halves of the brain and the other that runs between the brain and the spinal cord. The absence of such nerve tracts suggests that L1 is involved in the growth of axons within the embryonic nervous system."**
Cell adhesion molecule
Cell Adhesion Molecules are proteins located on the cell surface involved with the binding with other cells or with the extracellular matrix in the process called cell adhesion....
s that includes four different L1
L1 (protein)
L1, also known as L1CAM, is a transmembrane protein; it is a neuronal cell adhesion molecule, member of the L1 protein family, of 200-220 kDa, and involved in axon guidance and cell migration with a strong implication in treatment-resistant cancers....
-like proteins. They are members of the immunoglobulin superfamily (IgSF CAMs). The members of the L1-family in humans are called L1
L1
L1, L01, L.1, L 1 or L-1 may refer to:* L1 distance in mathematics, used in taxicab geometry* L1, the space of Lebesgue integrable functions in mathematics* L1 family, a protein family of cell adhesion molecules...
or L1cam, CHL1
CHL1
Neural cell adhesion molecule L1-like protein also known as close homolog of L1 is a protein that in humans is encoded by the CHL1 gene.CHL1 is a cell adhesion molecule closely related to the L1...
(close homologue of L1), Neurofascin and NrCAM
NRCAM
Neuronal cell adhesion molecule is a protein that in humans is encoded by the NRCAM gene.-Further reading:...
(NgCAM related cell adhesion molecule). L1 family members are found on neurons, especially on their axons. Sometimes they are found on glia, such as Schwann cells, radial glia
Radial glia
Radial glial cells are a pivotal cell type in the developing central nervous system involved in key developmental processes, from patterning and neuronal migration to their recently discovered role as precursors during neurogenesis. They arise early in development from neuroepithelial cells...
and Bergmann glia cells and, as such, are important for neural cell migration during development. L1 family members are expressed throughout the vertebrate and invertebrate kingdoms.
L1 family members are able to bind to a number of other proteins. As cell adhesion molecules, they often bind "homophilically" to themselves; for example L1 on one cell binding to L1 on an adjacent cell. L1 family members also bind "heterophilically" to members of the contactin or CNTN1
CNTN1
Contactin 1, also known as CNTN1, is a protein which in humans is encoded by the CNTN1 gene.- Function :The protein encoded by this gene is a member of the immunoglobulin superfamily. It is a glycosylphosphatidylinositol -anchored neuronal membrane protein that functions as a cell adhesion molecule...
family. L1 family members bind to many cytoplasmic proteins such as Ankyrin
Ankyrin
Ankyrins are a family of adaptor proteins that mediate the attachment of integral membrane proteins to the spectrin-actin based membrane skeleton. Ankyrins have binding sites for the beta subunit of spectrin and at least 12 families of integral membrane proteins...
s, ezrin-moesin-radixin (ERM) proteins, signaling molecules like src (src gene) and erk (Extracellular signal-regulated kinases
Extracellular signal-regulated kinases
In molecular biology, extracellular-signal-regulated kinases or classical MAP kinases are widely expressed protein kinase intracellular signalling molecules that are involved in functions including the regulation of meiosis, mitosis, and postmitotic functions in differentiated cells...
) and proteins important in trafficking, such as AP-2.
NrCAM and neurofascin both have class 1 PDZ domain binding motifs at their COOH termini. NrCAM can bind to SAP102 and other members of the MAGUK family.
Roles in the body:
"The importance of L1 in neural development has been revealed in several ways. In humans, mutations in the L1 gene can have devastating consequences. In extreme cases, babies are born with a fatal condition of hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
("water on the brain"). Children with less severe mutations typically exhibit mental retardation and difficulty in controlling limb movements (spasticity). Autopsies on patients that have died of an L1-deficiency disease reveal a remarkable condition: they are often missing two large nerve tracts, one that runs in the two halves of the brain and the other that runs between the brain and the spinal cord. The absence of such nerve tracts suggests that L1 is involved in the growth of axons within the embryonic nervous system."**
External links
- http://zygote.swarthmore.edu/cell9.html
- Gerald Karp. Cell and molecular Biology: Concepts and experiments 5th Edition. John Wiley & Sons: Asia. 2008 (pg. 257)