Forckenbeckstraße 6,

D-52074 Aachen

Nephrin is encoded by NPHS1 gene (chromosome 19q13.1), the core protein of the interpodocyte slit diaphragm of kidney glomerulus, this novel kidney specific protein was recently discovered. The mutated NPHS1 gene in congenital nephrotic syndrome of Finnish type, a human disease that leads to massive proteinuria in utero and nephrosis at birth. Nephrin is a transmembrane protein of immunoglobulin super family with 8 Ig like domains, identified in human (1241aa), rat (1252aa), and mouse (1256aa). Nephrin is found to be specifically expressed in kidney-slit diaphragm, brain and pancreas, the protein plays a crucial role in development and function of kidney filtration barrier, this barrier is crucial for maintaining the water and electrolyte balance without losing circulating proteins into the urine.

Nephrin interacts with podocin and with CD2AP C-terminal domain, It tends to be a signaling molecule that activates canonical protein kinase cascades, which is initiated by three closely related proteins called NEPH proteins (NEPH1, NEPH2, & NEPH3), The NEPH proteins share a common domain architecture consisting of 5 extracellular Ig domain followed by transmembrane domain, These proteins bind to C-terminal domain of podocin, which interacts with C-terminal of nephrin and greatly enhances nephrin-induced signaling. Filtrin a type I transmembrane protein belonging to immunoglobulin superfamily of cell adhesion molecules, due to its structural similarity and sequence homology with nephrin, it belongs to the functionally important complex of proteins of glomerular filtration barrier.

NEPH1 (Human 605aa, 67kD protein; Mouse 789aa, the sequence is 42.96%conserved between human and mouse). NEPH1 was identified in mice by a retrovirus mediated mutagenesis screening, contains 5 Ig like domains and is structurally related to nephrin. The protein has a putative signal sequence at N-terminus and a transmembrane region. Inactivation of NEPH1 develops a nephrotic syndrome that resembles NPHS mutations, suggesting that all three proteins are essential for the integrity of glomerular podocytes. NEPH1 is expressed in kidney, brain, and smooth muscle of liver, lung and heart.

NEPH2 (Human 778aa, chrm 11q24) has no N-terminal signal peptide; the C-terminus will be inside and do have transmembrane region. It has the common domain architecture of 5 Ig domains. NEPH2 id present in brain, heart, kidney and nervous system.

NEPH3 (Human 708aa, chrm 19q13.1, the NEPH3 gene is very adjacent to NPSH1gene of nephrin) has a intracellular N-terminal signal peptide and a transmembrane region, NEPH3 is present in kidney, lung, pituitary, germ cells and several tumor cell lines.

Podocin (Human 383aa, NPHS2 gene on 1q25-q31 chrm; Mouse 385aa, sequence homology is 83.12% between human and mouse) Mutations in NPHS2 gene causes the autosomal recessive form of steroid resistant nephrotic syndrome occurring mainly in children and is characterized by massive proteinuria. The protein has no signal peptide but a transmembrane region exists. Podocin plays a role in regulation of glomerular permeability and interacts with nephrin. Podocin is expressed in kidney, testis, fetal heart and liver.

Podocalyxin, a 485aa protein in rat and 528aa in human (chr 7q32-q33). Functions as an antiadhesin that maintains an open filtration pathway between neighboring foot processes in the podocytes by charge repulsion. Mainly expressed in Glomerular epithelium cells.

Filtrin (Human 219aa, 107kD, chrm 19q13.12, gene NLG1) belongs to the functionally important glomerular filtration barrier proteins, Filtrin is a nehrin-like protein expressed in glomeruli, It has structural similarity and partial consistent expression with nephrin, thus shows 30% and 44% homology with nephrin and NEPH1 respectively.

Rb=rabbit; m=mouse; r=rat; h=human; b=bovine; c=chicken; d=dog; ~CT or ~NT=near C or N-terminus. EC=Extracellular; CL=Cytoplasmic loop.

* Expected antibody crossreactivity information is mostly based upon high (>70%) sequence conservation of antigenic/control peptides in various species. When antibody crossreactivity has actually been experimentally confirmed in various species, it will be mentioned in the appropriate data sheets.

"Neat Antisera or antisera" are the unpurified antiserum and it is suitable for ELISA and Western.
"Affinity pure" IgG may be more suitable for immunohistochemical (IHC) applications and to reduce background in most immunological applications including ELISA and Western.
"Control peptides" can not be used for Western as they are very short peptides. They are intended for ELISA or antibody blocking studies to establish antibody specificity.
Western blot +ve protein controls, where available, are semi-pure, pure or recombinant proteins that are formulated in SDS-PAGE sample buffer. They are recommended to be used for Western (load 10 ul/lane) for visualization with antibodies.
 

© 2005 GENTAUR bvba
 

Bioxys, HIV p24, TNF a, IFN gamma, Agarose