Nucleic acid reporter molecules for massively parallel DNA sequencing

A pool of multiple nucleic acid reporter molecule species for use in a massively parallel DNA sequencing method, wherein all members of an individual nucleic acid reporter molecule species have identical nucleic acid sequences, wherein the members of each nucleic acid reporter molecule species comprise, in order from 3′-end to 5′-end:

• (i) a first sequencing adapter,
• (ii) a first identification (ID) sequence,
• (iii) a first hybridisation sequence, or a first hybridisation sequence and a second hybridisation sequence,
• (iv) a second ID sequence, and
• (v) a second sequencing adapter,
• wherein the combination of the first ID sequence and the second ID sequence of each individual nucleic acid reporter molecule species is different from the combination of the first ID sequence and the second ID sequence of the other nucleic acid reporter molecule species in the pool and wherein the ID sequences are barcode sequences each of which corresponds to a particular protein analyte,
• wherein the first hybridisation sequence is or the first hybridisation sequence and the second hybridisation sequence are, respectively, the same in a plurality of different nucleic acid reporter molecule species, and
• wherein the sequencing adapters are the same in all nucleic acid reporter molecule species.