Editing Podocyte (section)

== Function ==
[[File:Filtration barrier.svg|300px|thumb|Scheme of filtration barrier (blood-urine) in the kidney.<br> A. The endothelial cells of the glomerulus; 1. pore (fenestra).<br>
B. Glomerular basement membrane: 1. lamina rara interna 2. lamina densa 3. lamina rara externa<br>
C. Podocytes: 1. enzymatic and structural protein '''2. filtration slit''' 3. diaphragma]]
Podocytes have primary processes called trabeculae, which wrap around the [[glomerular capillaries]].<ref name="Ovalle" /> The trabeculae in turn have [[Foot process|secondary processes]] called pedicels or foot processes.<ref name="Ovalle"/> Pedicels interdigitate, thereby giving rise to thin gaps called filtration slits.<ref name="lote" /> The slits are covered by slit diaphragms which are composed of a number of cell-surface proteins including [[nephrin]], [[podocalyxin]], and [[cadherin|P-cadherin]], which restrict the passage of large [[macromolecules]] such as [[serum albumin]] and [[gamma globulin]] and ensure that they remain in the bloodstream.<ref>{{cite journal | vauthors = Jarad G, Miner JH | title = Update on the glomerular filtration barrier | journal = Current Opinion in Nephrology and Hypertension | volume = 18 | issue = 3 | pages = 226–232 | date = May 2009 | pmid = 19374010 | pmc = 2895306 | doi = 10.1097/mnh.0b013e3283296044 }}</ref> Proteins that are required for the correct function of the slit diaphragm include [[nephrin]],<ref>{{cite journal | vauthors = Wartiovaara J, Ofverstedt LG, Khoshnoodi J, Zhang J, Mäkelä E, Sandin S, Ruotsalainen V, Cheng RH, Jalanko H, Skoglund U, Tryggvason K | display-authors = 6 | title = Nephrin strands contribute to a porous slit diaphragm scaffold as revealed by electron tomography | journal = The Journal of Clinical Investigation | volume = 114 | issue = 10 | pages = 1475–1483 | date = November 2004 | pmid = 15545998 | pmc = 525744 | doi = 10.1172/JCI22562 }}</ref> [[KIRREL|NEPH1]], [[KIRREL3|NEPH2]],<ref>{{cite journal | vauthors = Neumann-Haefelin E, Kramer-Zucker A, Slanchev K, Hartleben B, Noutsou F, Martin K, Wanner N, Ritter A, Gödel M, Pagel P, Fu X, Müller A, Baumeister R, Walz G, Huber TB | display-authors = 6 | title = A model organism approach: defining the role of Neph proteins as regulators of neuron and kidney morphogenesis | journal = Human Molecular Genetics | volume = 19 | issue = 12 | pages = 2347–2359 | date = June 2010 | pmid = 20233749 | doi = 10.1093/hmg/ddq108 | doi-access =  }}</ref> [[podocin]], [[CD2AP]].<ref>{{cite journal | vauthors = Fukasawa H, Bornheimer S, Kudlicka K, Farquhar MG | title = Slit diaphragms contain tight junction proteins | journal = Journal of the American Society of Nephrology | volume = 20 | issue = 7 | pages = 1491–1503 | date = July 2009 | pmid = 19478094 | pmc = 2709684 | doi = 10.1681/ASN.2008101117 }}</ref> and [[FAT1]].<ref>{{cite journal | vauthors = Ciani L, Patel A, Allen ND, ffrench-Constant C | title = Mice lacking the giant protocadherin mFAT1 exhibit renal slit junction abnormalities and a partially penetrant cyclopia and anophthalmia phenotype | journal = Molecular and Cellular Biology | volume = 23 | issue = 10 | pages = 3575–3582 | date = May 2003 | pmid = 12724416 | pmc = 164754 | doi = 10.1128/mcb.23.10.3575-3582.2003 }}</ref>
[[File:Podo001.jpg|upright=1.5|thumb|The protein composition of podocytes and the slit diaphragm.]]
Small molecules such as [[water]], [[glucose]], and [[ion]]ic salts are able to pass through the filtration slits and form an [[ultrafiltrate]] in the [[tubular fluid]], which is further processed by the [[nephron]] to produce [[urine]].

Podocytes are also involved in regulation of [[glomerular filtration rate]] (GFR). When podocytes contract, they cause closure of filtration slits. This decreases the GFR by reducing the surface area available for filtration.