Proteins are dynamic molecules that regulate a myriad of cellular functions; these functions may be regulated by protein post-translational modifications (PTMs) that mediate the activity, localization and interaction partners of proteins. Thus, understanding the meaning of a single PTM or the combination of several of them is essential to unravel the mechanisms of protein regulation. Yeast Amino Acid Modification (YAAM) (http://yaam.ifc.unam.mx) is a comprehensive database that contains information from 121 921 residues of proteins, which are post-translationally modified in the yeast model Saccharomyces cerevisiae. All the PTMs contained in YAAM have been confirmed experimentally. YAAM database maps PTM residues in a 3D canvas for 680 proteins with a known 3D structure. The structure can be visualized and manipulated using the most common web browsers without the need for any additional plugin. The aim of our database is to retrieve and organize data about the location of modified amino acids providing information in a concise but comprehensive and user-friendly way, enabling users to find relevant information on PTMs. Given that PTMs influence almost all aspects of the biology of both healthy and diseased cells, identifying and understanding PTMs is critical in the study of molecular and cell biology. YAAM allows users to perform multiple searches, up to three modifications at the same residue, giving the possibility to explore possible regulatory mechanism for some proteins. Using YAAM search engine, we found three different PTMs of lysine residues involved in protein translation. This suggests an important regulatory mechanism for protein translation that needs to be further studied. Database URL: http://yaam.ifc.unam.mx/

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Algunas reflexiones sobre la representación del tiempo en la imaginería maya antigua Some thoughts on the representation of time in Classic Maya imagery Quelques réflexions sur la représentation du temps dans l'imagerie maya classique

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We wish to discuss some of the multiple Maya meanings that surround the human body and the role of its vital components in ritualized violence, specifically the forms of self-sacrifice and human sacrifice itself. This essay offers a series of elements of discussion that are key to detecting and understanding the transformations of the body and its components during ritual death along with the markers that give them away in the mortuary record; the proposals put forward here were thought from the perspective of data from the lowlands during the Late Classic period (600-800 ad), although it is feasible to assume that some aspects date from earlier tiemes or survived in more recent times.