<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Muchmore, E. A.</style></author><author><style face="normal" font="default" size="100%">Diaz, S.</style></author><author><style face="normal" font="default" size="100%">Ajit Varki</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A structural difference between the cell surfaces of humans and the great apes</style></title><secondary-title><style face="normal" font="default" size="100%">Am J Phys Anthropol</style></secondary-title><alt-title><style face="normal" font="default" size="100%">American journal of physical anthropology</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">*Hominidae</style></keyword><keyword><style  face="normal" font="default" size="100%">*Phylogeny</style></keyword><keyword><style  face="normal" font="default" size="100%">Animals</style></keyword><keyword><style  face="normal" font="default" size="100%">Evolution</style></keyword><keyword><style  face="normal" font="default" size="100%">Gangliosides/*metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydroxylation</style></keyword><keyword><style  face="normal" font="default" size="100%">Membrane Proteins/*physiology</style></keyword><keyword><style  face="normal" font="default" size="100%">Molecular</style></keyword><keyword><style  face="normal" font="default" size="100%">Sialic Acids/metabolism</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1998</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Oct</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/9786333</style></url></web-urls></urls><number><style face="normal" font="default" size="100%">2</style></number><edition><style face="normal" font="default" size="100%">1998/10/24</style></edition><volume><style face="normal" font="default" size="100%">107</style></volume><pages><style face="normal" font="default" size="100%">187-98</style></pages><isbn><style face="normal" font="default" size="100%">0002-9483 (Print)0002-94</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The sialic acids are major components of the cell surfaces of animals of the deuterostome lineage. Earlier studies suggested that humans may not express N-glycolyl-neuraminic acid (Neu5Gc), a hydroxylated form of the common sialic acid N-acetyl-neuraminic acid (Neu5Ac). We find that while Neu5Gc is essentially undetectable on human plasma proteins and erythrocytes, it is a major component in all the four extant great apes (chimpanzee, bonobo, gorilla and orangutan) as well as in many other mammals. This marked difference is also seen amongst cultured lymphoblastoid cells from humans and great apes, as well as in a variety of other tissues compared between humans and chimpanzees, including the cerebral cortex and the cerebrospinal fluid. Biosynthetically, Neu5Gc arises from the action of a hydroxylase that converts the nucleotide donor CMP-Neu5Ac to CMP-Neu5Gc. This enzymatic activity is present in chimpanzee cells, but not in human cells. However, traces of Neu5Gc occur in some human tissues, and others have reported expression of Neu5Gc in human cancers and fetal tissues. Thus, the enzymatic capacity to express Neu5Gc appears to have been suppressed sometime after the great ape-hominid divergence. As terminal structures on cell surfaces, sialic acids are involved in intercellular cross-talk involving specific vertebrate lectins, as well as in microbe-host recognition involving a wide variety of pathogens. The level of sialic acid hydroxylation (level of Neu5Ac versus Neu5Gc) is known to positively or negatively affect several of these endogenous and exogenous interactions. Thus, there are potential functional consequences of this widespread structural change in humans affecting the surfaces of cells throughout the body.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">Research Support, Non-U.S. Gov&#039;tResearch Support, U.S. Gov&#039;t, P.H.S.</style></work-type><notes><style face="normal" font="default" size="100%">&lt;p&gt;Am J Phys Anthropol. 1998 Oct;107(2):187-98&lt;/p&gt;</style></notes><auth-address><style face="normal" font="default" size="100%">UCSD Cancer Center, Division of Hematology-Oncology, University of California San Diego, La Jolla 92093-0687, USA.</style></auth-address></record></records></xml>