Central JSM Biotechnology & Biomedical Engineering Cite this article: Kanan Y, Al-Ubaidi MR (2013) Tyrosine O Sulfation: An Overview. JSM Biotechnol Bioeng 1(1): 1003. Corresponding author Yo g ita Ka na n, De p a rtm e nt o f C e ll Bio lo g y, Unive rsity o f O kla ho m a He a lth Sc ie nc e s C e nte r, BMSB 781, 940 Stanto n L. Yo ung Blvd., Oklaho ma City, OK 73104, USA, Tel: (405) 271-2408; Fax: (405) 271-3548; Email: yka na n@ o uhsc .e d u Submitte d: 19 July 2013 Accepted: 14 August 2013 Publishe d: 16 August 2013 Copyright © 2013 Ka na n a nd Al-Ub a id i OPEN ACCESS Ke ywo rds • Tyro sine -sulfa te • Tyro sine O sulfa tio n Review Article Tyrosine O Sulfation: An Overview Yogita Kanan* and Muayyad R. Al-Ubaidi Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, USA Abstract Tyrosine O sulfation is a post translational modiication (PTM) originally discovered by Bettelheim in 1954 in the bovine protein ibrinogen. Currently, this PTM is found only in secreted and transmembrane proteins of higher eukaryotes. This article gives an overview of experimental tools to study tyrosine O sulfation and also describes the biological function of this PTM. INTRODUCTION The Tyrosine O sulfation reaction is catalyzed by two Type II transmembrane enzymes, tyrosylprotein sulfotransferases 1 & 2 (TPST 1 & 2). Huttner identified the trans-golgi as the compartment in which this PTM occurred [1]. The sulfate donor for the reaction is 3′-phosphoadenosine 5′-phosphosulfate (PAPS). The major feature of the sulfated tyrosines is the presence of acidic amino acids within ± 5 residues of the sulfated residues [2,3]. Figure 1 shows the schematic representation of the tyrosine O sulfation reaction in the trans-golgi compartment. Currently, only secreted and transmembrane proteins of higher eukaryotes are subject to this PTM. To study the role of tyrosine sulfation in-vivo, knockout animals were generated that had targeted gene disruptions in the genes that code for TPST 1 [4] or 2 [5]. Studies on these animals showed a distinct phenotype for each animal, suggesting no functional redundancy between TPST 1 and TPST 2. Tpst1 −/− animals had a 5% lower average body weight compared to wild- type animals and the Tpst1 −/− females had smaller litter sizes due to increased post implantation fetal death [4]. In addition, retinal function of these animals is compromised as assessed by reduced rod ERG function in early development, but these retinas become electrophysiologically normal by postnatal day 90 [6]. Tpst2 −/− animals had reduced body weight compared to age matched wild-type animals, and the males are sterile. In-vitro fertilization assays in these animals showed fewer eggs were able to be fertilized by sperm from Tpst2 −/− males. Further analysis of Tpst2 −/− sperm showed a decreased motility in viscous media and an inability to penetrate zona pellucida of intact eggs [5]. Retinal function of these animals is also compromised as assessed by reduced rod ERG and cone ERG values, that do not become electrophysiologically normal during the entire age of the animal [6]. Double knockout animals (DKO) generated by selective matings between the two individual knockout animals [7] had 95% mortality by postnatal day 5 and no animal survived beyond 2 months of age [7]. Autopsy studies on these pups indicated poor aeration of the lungs due to improper expansion of the alveoli. The hearts of these animals were also abnormal due to the enlargement of the atrium and vena cava. And, in addition to these effects, the follicles of the thyroid gland were devoid of colloid suggesting that these animals are hypothyroid [7]. These animals also had the most drastically reduced visual function as assessed by the rod and cone ERG values becoming 25% and 15% of normal wild-type levels, respectively [8]. The rod and cone synaptic terminals were disorganized and defects were seen in their ultrastructure at the EM level [8]. DETECTION METHODS Tyrosine O sulfation in proteins can be detected by radioactive and non-radioactive methods. Non-radioactive methods Two antibodies are widely used to identify tyrosine-sulfated proteins [9,10]. These antibodies were developed using phage display technology. The epitope for both antibodies was the tyrosine-sulfated N-terminal region of PSGL-1 [9,10]. Therefore, a limitation to using these antibodies to identify tyrosine-sulfated protein is that both antibodies identify tyrosine-sulfate residue Figure 1 Tyrosine O sulfation reaction. The enzyme tyrosylprotein sulfotransferase (TPST) in the trans-golgi compartment, transfers a sulfate group from the universal sulfate donor 3′-phosphoadenosine-5′-phosphosulfate (PAPS) to the tyrosine residue in the protein, resulting in the formation of a tyrosine O sulfate ester and 3′,5′-ADP (PAP).