Abstract: Provided is a galvanized steel sheet having a TS of 980 MPa or more, high YS, excellent ductility, strain hardenability, and hole expansion formability. A base steel sheet has a defined chemical composition and a steel microstructure as follows: area ratio of ferrite: 65.0% or less (including 0%), area ratio of bainitic ferrite: 5.0% or more and 40.0% or less, area ratio of tempered martensite: 0.5% or more and 80.0% or less, area ratio of retained austenite: 3.0% or more, area ratio of fresh martensite: 20.0% or less (including 0%), SBF+STM+2×SMA: 65.0% or more, SMA1/SMA: 0.80 or less, and SMA2/SMA: 0.20 or more.

Abstract: Described herein is a polynucleotide encoding a fusion protein comprising two or more polypeptide domains and a polypeptide linker joining the domains, wherein the sequence of the polynucleotide encoding the polypeptide linker is selected such that when the mRNA transcribed from the polynucleotide is translated in a host cell transfected with the polynucleotide, the translation rate of the mRNA region encoding the polypeptide linker is slower than the translation rate of the mRNA region encoding the polypeptide domain immediately upstream thereof. Also provided are a vector transfected with the polynucleotide of the present invention so that the polynucleotide can be expressed in the host cell; a host cell transformed by that vector; and a process for producing a fusion protein comprising culturing the host cell, and recovering the fusion protein thus produced.