{{Short description|Mammalian protein found in Homo sapiens}} {{Infobox_gene}} '''Guanine deaminase''' also known as '''cypin''', '''guanase''', '''guanine aminase''', '''GAH''', and '''guanine aminohydrolase''' is an aminohydrolase enzyme which converts guanine to xanthine.<ref>{{cite journal | vauthors = Hitchings GH, Falco EA | title = The Identification of Guanine in Extracts of Girella Nigricans: The Specificity of Guanase | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 30 | issue = 10 | pages = 294–7 | date = Oct 1944 | pmid = 16578130 | pmc = 1078714 | doi = 10.1073/pnas.30.10.294 | bibcode = 1944PNAS...30..294H | doi-access = free }}</ref><ref name="pmid20285041">{{cite journal | vauthors = Kalckar HM | title = Differential spectrophotometry of purine compounds by means of specific enzymes; studies of the enzymes of purine metabolism | journal = J. Biol. Chem. | volume = 167 | issue = 2 | pages = 461–75 | year = 1947 | doi = 10.1016/S0021-9258(17)30999-7 | pmid = 20285041 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Rabinowitz JC, Barker HA | title = Purine fermentation by Clostridium cylindrosporum. II. Purine transformations | journal = The Journal of Biological Chemistry | volume = 218 | issue = 1 | pages = 161–73 | date = Jan 1956 | doi = 10.1016/S0021-9258(18)65881-8 | pmid = 13278325 | doi-access = free }}</ref> Cypin is a major cytosolic protein that interacts with PSD-95. It promotes localized microtubule assembly in neuronal dendrites.<ref name="pmid10595517">{{cite journal | vauthors = Firestein BL, Firestein BL, Brenman JE, Aoki C, Sanchez-Perez AM, El-Husseini AE, Bredt DS | title = Cypin: a cytosolic regulator of PSD-95 postsynaptic targeting | journal = Neuron | volume = 24 | issue = 3 | pages = 659–72 | year = 1999 | pmid = 10595517 | doi = 10.1016/S0896-6273(00)81120-4| doi-access = free }}</ref>
600px|thumb|center|Xanthine synthesis from guanine
== References == {{reflist}}
== External links == * {{MeshName|Guanine+deaminase}} * {{PDBe-KB2|Q9Y2T3|Human Guanine deaminase}}
{{Nucleotide metabolism}} {{Carbon-nitrogen non-peptide hydrolases}} {{Enzymes}} {{Portal bar|Biology|border=no}}
Category:EC 3.5.4
{{3.5-enzyme-stub}}