read_uniprot(connection, what = "signal", euk)connection to UniProt data in text format.NULL or a single character determining which information
should be extracted. Currently can have following values: "signal",
"transit" or NULL.SeqFastaAA.
Attribute sig contains the range (start and end) of signal peptide. Attributes
OS and OC represents respectively OS and OC fields in the protein
description. Sequence with more than one cleavage site or atypical aminoacids
are removed without any notice.