Nidogens, formerly known as entactins, are a family of sulfated

monomer In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Mo ...

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

s located in the

basal lamina The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, though it does constitute a portion of the basement membrane. The ba ...

of parahoxozoans. Two nidogens have been identified in humans:

nidogen-1 Nidogen-1 (NID-1), formerly known as entactin, is a protein that in humans is encoded by the ''NID1'' gene. Both nidogen-1 and nidogen-2 are essential components of the basement membrane alongside other components such as type IV collagen, proteogl ...

(NID1) and

nidogen-2 Nidogen-2, also known as osteonidogen, is a basal lamina protein of the nidogen family. It was the second nidogen to be described after nidogen-1 (entactin). Both play key roles during late embryonic development. In humans it is encoded by the ''N ...

(NID2). Remarkably,

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

s are still capable of stabilizing

basement membrane The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...

in the absence of either identified nidogen. In contrast, those lacking both nidogen-1 and nidogen-2 typically die prematurely during embryonic development as a result of defects existing in the heart and lungs. Nidogen have been shown to play a crucial role during

organogenesis Organogenesis is the phase of embryonic development that starts at the end of gastrulation and continues until birth. During organogenesis, the three germ layers formed from gastrulation (the ectoderm, endoderm, and mesoderm) form the internal orga ...

in late

embryonic development An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

, particularly in cardiac and lung development. From an evolutionary perspective, nidogens are highly conserved across vertebrates and invertebrates, retaining their ability to bind

laminin Laminins are a family of glycoproteins of the extracellular matrix of all animals. They are major components of the basal lamina (one of the layers of the basement membrane), the protein network foundation for most cells and organs. The laminins ...

. In

nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...

, nidogen-1 is necessary for

axon guidance Axon guidance (also called axon pathfinding) is a subfield of neural development concerning the process by which neurons send out axons to reach their correct targets. Axons often follow very precise paths in the nervous system, and how they mana ...

, but not for basement membrane assembly.

References

Human proteins Protein families Extracellular matrix proteins {{Biochemistry-stub