Podocalyxin-like protein 1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''PODXL''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
This gene encodes a member of the CD34 sialomucin protein family.
The encoded protein was originally identified as an important component of glomerular podocytes. Inactivation of the encoding gene in mice leads to anuria, omphalocele and perinatal death.
Podocytes are highly differentiated epithelial cells with interdigitating foot processes covering the outer aspect of the glomerular basement membrane. Other biological activities of the encoded protein include: binding in a membrane protein complex with Na+/H+ exchanger regulatory factor to intracellular cytoskeletal elements, playing a role in hematopoietic cell differentiation, and being expressed in vascular endothelium cells and binding to L-selectin.
Expression
The expression and localisation of PODXL in human cells, tissues and organs have been investigated by the
Human Protein Atlas consortium. According to
antibody
An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
-based profiling, the protein is present in
glomerular
''Glomerulus'' (; : glomeruli) is a common term used in anatomy to describe globular structures of entwined vessels, fibers, or neurons. ''Glomerulus'' is the diminutive of the Latin ''glomus'', meaning "ball of yarn".
''Glomerulus'' may refer to ...
podocytes
Podocytes are cells in Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus. Podocytes make up the epithelial lining of Bowman's capsule, the third layer through which filtration of blood takes place. Bowman's capsule ...
,
endothelial cells
The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the res ...
,
glandular cells in
fallopian tube
The fallopian tubes, also known as uterine tubes, oviducts or salpinges (: salpinx), are paired tubular sex organs in the human female body that stretch from the Ovary, ovaries to the uterus. The fallopian tubes are part of the female reproduct ...
,
uterus
The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...
and
seminal vesicle
The seminal vesicles (also called vesicular glands or seminal glands) are a pair of convoluted tubular accessory glands that lie behind the urinary bladder of male mammals. They secrete fluid that largely composes the semen.
The vesicles are 5 ...
and according to RNA expression analysis, the PODXL transcripts are present in all analysed human tissues. Based on
confocal microscopy
Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast (vision), contrast of a micrograph by me ...
, the protein is mainly localised to the
plasma membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
and
microtubule
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...
organizing center and in addition localized to
vesicles
Vesicle may refer to:
; In cellular biology or chemistry
* Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane
* Synaptic vesicle
In a neuron, synaptic vesicles (or neurotransmitter vesicles) s ...
.
Interactions
PODXL has been shown to
interact with
Sodium-hydrogen exchange regulatory cofactor 2
Sodium-hydrogen exchange regulatory cofactor NHE-RF2 (NHERF-2) also known as tyrosine kinase activator protein 1 (TKA-1) or SRY-interacting protein 1 (SIP-1) is a protein that in humans is encoded by the ''SLC9A3R2'' (solute carrier family 9 isof ...
.
Clinical significance
Podocalyxin is upregulated in a number of cancers and is frequently associated with poor prognosis. Based on patient survival data,
[Uhlen et al (2017) Science 357 (6352): eaan2507. https://doi.org/doi:10.1126/science.aan2507] high level of PODXL transcripts in tumor cells is associated with poor prognosis in renal cancer.
References
Further reading
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