instruction:
In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
question:
Human and murine cytotoxic T lymphocyte serine proteases : subsite mapping with peptide thioester substrates and inhibition of enzyme activity and cytolysis by isocoumarins .
answer:
serine proteases

question:
Although polyubiquitin chains linked through Lys ( 29 ) of ubiquitin have been implicated in the targeting of certain substrates to proteasomes , the signaling properties of these chains are poorly understood .
answer:
polyubiquitin chains

question:
The hematopoietic form of PTPN6 transcript is initiated at a downstream promoter separated by 7 kb from the first .
answer:
PTPN6 transcript