The literal answer is that half an "X" is not a non-functional half-letter, it is either a forward slash or backslash or a "V" or caret, all of which work just fine for different functions.
As such, the outcome is a descriptive indication of the functional level of letter identification possible rather than a formal visual acuity measure.
By clicking on the one-letter functional class code, a page displaying a list of all proteins classified in this specific category is presented, with links to the corresponding BLAST alignments.
For an adequate description of the pH-dependent charge state of side-chain and terminal amino acid functional groups, the one-letter code may be extended: For example, at a pH value of 7.4 the pentapeptide RRHIS contains a positively charged amino group at the terminal arginine, two positively charged arginine side chains and a negatively charged carboxylic group at the terminal serine.
Functional terms in bold letters represent the p values after removing the overlap of germ cell-enriched expression (Fig. 5) from the respective groups.
A functional localiser of these early letter-specific responses was developed for the production of functional regions of interest in future studies.
Inspired by taxonomic best practices, the tentative classification system described in this paper proposes that each EPA on PsychTable be assigned a three-letter symbol, a functional class, and a classification number, similar to the Periodic Table of the Elements.
Among the first desaturase subfamily, several groups have been recognized based on phylogenetic and functional analysis and a four-letter "signature motif" has been suggested for each of them as shown in Fig. 6.
In the KOG database [ 21, 22] human genes were classified in 25 functional classes, denoted by capital letters in square brackets, and grouped in three main categories: i) information storage and processing, represented by five functional classes; ii) cellular processes and signaling, represented by ten functional classes; and iii) metabolism, represented by eight functional classes.
In the KOG database http://www.ncbi.nlm.nih.gov/COG/[ 21, 22] human proteins were grouped in functional classes (denoted by capital letters in square brackets), in turn grouped in three large categories, namely: (i) information storage and processing; (ii) cellular processes and signaling; (iii) metabolism.
